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Thrown Silk.

lbs.

.

Agonal arerage.

£.

.

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Waste, Knubs,

manufacture was anything but satisfactory; the manufac-
Raw Silk. and Husks.
lbs.
lbs.

turers complaining of the smuggling of foreign silks, par-
India
1,385,932 2,012

liament vainly endeavouring to exclude them, with constant China . 349,549 10,951

disputes about wages on the part of the weavers. In 1773 Turkey, Syria,

they obtained an act, called the Spitalfields Act, which and Egypt . 731,121

entitled the Middlesex weavers to demand fixed wages, to Italy 181,743 436,819

755 le settled by the magistrates. To this act may be attributed France

1,018,901 568,754 213,991 the establishment of the silk manufacture in various parts Other countries 79,002 23,954 10,522 of the country; and having done great mischief, it was

repealed in 1824. The changes introduced in 1824 (some Total 3,746,248 1,042,490 225,268 of which only came into operation July 5th, 1826), wiih a

view of stimulating the silk manufacture, have been most The duty on raw silk is 1d. per Ib.; on waste, knubs, and successful, as the table of the consumption of silk, bchusks, 18. per cwt.; and on thrown silk the following duties fore and after the duties were reduced, sufficiently proves. are imposed :-58. 2d. per lb. on organzine and crape, and Now that silk has become cheaper, and consequently a 38 on iram and singles, dyed; 38. 6d. on organzine and

commoner article of dress, it is less dependent on the caprice crapes, 28. on tram, and is. 6d. on singles, not dyed. It is of fashion than when it was an expensive luxury. The objected to this duty on foreign-thrown silk that it raises declared value of silk goods exported since 1820 is shown unnecessarily the price of all silk thrown at home. A draw- in the following table: back is allowed on the exportation of foreign-thrown silk : no British-thrown silk is exported. The first silk-throwing mill erected in England was at Derby, in 1718. (Derby.]

1820 to 1823 (inclusive)

369,835 Reeling from the cocoons is only performed in countries

1824 to 1827

286,119 where the silk is produced. Silk reaches the weaver in

1828 to 1831

403,961 three different states, in which it is called singles, tram, and

1832 to 1835

693,961 organzine (RIBAND), the preparation of which is the busi 1836 to 1840

771,479 ness of the throwster. In plain silk-weaving the process is The declared value of silk manufactures exported in 1839 much the same as in weaving woollen or linen; but the was 868,1181.: of which the United States of America took wearer is assisted by a machine for the even distribution of 410.0931.; British North America, 136,7501.; Australian the warp, which frequently consists of eight thousand settlements, 46,7241.; France, 44,6281.; British West separate ihreads in a breadth of twenty inches. The Jac- | Indies, 38,4671.; Chili, 44,733l.; Brazil, 23,1171. ; other quard loom, invented by a weaver of Lyon, has been the states of Central and Southern America, 49,0601.; Germany, means of facilitating and cheapening the production of fancy 17,135l.; East Indies and Ceylon, 14,7131. í Holland, or figured silks to an extraordinary extent. Patterns which 14,3061.; Belgium, 10,316l.; all other parts, 18,136l. required the greatest degree of skill and the most painful The value of the silk manufactures of Great Britain is labour are produced by this machine by weavers of ordinary estimated at between 6,000,0002. and 7,000,0001. One-half skill, and with but litile more labour than that required in of the silk factories are in Cheshire, next to which stand weaving plain silks. The Jacquard loom has been im- Lancashire, Somerset, Derbyshire, and Staffordshire. There proved by Mr. Hughes and Mr. Jennings, but at Lyon it are one or more factories in above one-half of the counties has undergone no alteration. The power-loom has been of England; one or two factories have been established in only partially employed in the silk manufacture, and ex- Ireland, and a few more in Scotland. They employ altocepting for the commonest goods, it does not possess any gether in these factories above 30,000 persons, of whom great advantage over the band-loom, as the delicacy of the two-thirds are females. material to be worked, and the attention which must be The duty on silk manufactured goods imported from given to the process of the weft, frequently render it neces. European countries is equivalent to 30 per cent. ad vasary to stop the machine.

lorem. In 1839 this duty produced 227,4381., and the Brocade and damask, the most sumptuous articles of silk value of the goods was therefore about 700,0001., nine-tenths manufacture a century ago, are now comparatively unknown. of which were from France. The exportation of silk goods Persian, sarsnet, gros-de-Naples, ducapes, satin, and levan- from France to England was 3,589,594 lbs. from 1827 to tines, are the names given to plain silks, which vary from 1838; but the quantity entered at the English customone another only in texture, quality, or softness. Satin house was only 1,875,708 lbs., and there were therefore derives its lustre from the great proportion of the threads 1,713,886 lbs. introduced by smuggling, or 48 per cent of the of the warp being left visible, and the piece being afterwards total quantity entered at the French custom-house for ex: passed over heated cylinders. Other varieties of silk goods portation to England. The duty on the legally imported are produced by mechanical arrangements in the loom, such goods averaged 20s. 4d. per lb. ; but if the illegal imporis as using different shuttles with threads of various substances, could have been charged also, a duty of 10s. Ild. would &c. The pile which constitutes the peculiarity of velvet is have produced the same revenue. (Table by G. R. Porter, produced by the insertion of short pieces of silk thread, Esq., of the Board of Trade, in the Report of Committee on which cover the surface so entirely as to conceal the inter- Import Duties ) lacings of the warp and woof. The process of weaving The silk manufactures of India are subject to an ad vavelvet is slow, and it is paid for at five times the rate of plain lorem duty of 20 per cent., which, in 1839, produced silks. There are several sorts of goods in which silk is em- | 19,8671. The imports consisted in that year of 503,182 ployed with woollen materials, as poplins and bombazines. pieces of bandannoes, romals, and silk handkerchiefs, of The Chinese, says Mr. Davis (p. 286), make a species of which only 112,280 paid duty for consumption in this washing silk, called at Canton 'ponge,' which becomes inore country; and of other articles the greater part were re-exsoft as it is longer used. Their crapes have never yet been ported. perfectly imitated; and they particularly excel in the pro ( Treutise on the Silk Manufacture, in Lardner's Cycloduction of damasks and flowered satins.

pædia ;' Ure's Philosophy of Manufactures ; Manual for The silk manufacture, after its introduction into England the Culture of Silk, prepared by order of the Massachusetts in the fifteenth century, remained for a long period one of Legislature, Boston, 1832; Essays on American Silk, with the least important branches of the national industry. Directions for raising Silk-worms, Philadelphia, 1830; After the revoeation of the Edict of Nantes, in 1685, about Second Report on Commercial Relations between Great 50,000 refugees fled to England, a large proportion of whom Britain and France (Silk), 1835.) settled in Spitalfields, and carried on the siik manufacture. SILK-WORM. [BOMBYCIDÆ.] At this period foreign silks were freely admitted; and SILLIMANITE, a crystallized silicate of alumina. It from 1685 to 1692, silks to the value of from 600,0007, to occurs in rhombic prisms imbedded in quartz. Cleavage 700.0001. were annually imported. In 1692 the refugees parallel to the long diagonal. Colour dark brownish-grey or obtained an exclusive patent for certain articles; and in close-brown. Fracture uneren, splintery. Specific gravity 1697 parliament probibited the importation of French and 3:41. Lustre vitreous, nearly adamantine on the face of other silk goods; and in 1701 the silk goods of India and cleavage. Nearly opaque. Hardness 8.0 to 8.5. Brittle China were included in the prohibition. Some inconsiderable and easily reduced to powder. relaxation was made in this policy in 1713, but in 1765 the It is inet with at Saybrook, Connecticut, North America. system of prohibition was again fully adopted, and continued It was at one time considered to be a variety of anthophylin operation until 1824. During this period the state of the lite, but it is much harder than this mineral, and coniains

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more alumina and less silica and oxide of iron. It more which show that the order of physical changes and organic nearly resembles sienite both in form and composition. combinations which characterise the Silurian System, was It yielded by the analysis of Bowen

in operation both before and after the period included in Silica

42.67

the ages of the four Silurian groups of “Llandeilo,' CaraAlumina

54:11

doc,' ' Wenlock,' and 'Ludlow;' while in other districts Oxide of Iron

2.00

these characteristic assemblages do not all clearly appear; Water

0:51-99.29 and thus we are naturally conducted to a more comprehensivo SI'LPHIUM (ortplov). Antient authors mention this view of the whole of the antient (Palæozoic).formations. plant and its juice. In the article on Laser, it has been Whatever be the true theory of the origin of the Granistated that two kinds are described of this substance, which toid Strata of gneiss and mica schist (with their many and is also called juice of silphium. One kind, from Cyrene, various quartzose, chloritic, and calcareous accompaniments), was probably yielded by Thapsia Silphium [Laser), and it is at least certain, as a general rule, that rocks of this the other was most likely assafætida, which has been em general type are prevalent among the very deepest and ployed medicinally by Asiatics from very early times, though oldest deposits from water which retain proof of their watery it has been known by this name in comparative modern aggregation, and that they are in this position devoid of the times.

traces of antient life. Silphium was however remarkable for other properties, Equally certain is the character of the great series of and hence has attracted the attention of modern travellers Neptunian rocks which lies upon the mica schist; it is a who have recently visited the countries where the silphium vast and various mass of strata (principally argillaceous, is described as growing by the antients. The army of locally arenaceous or conglomeritic, rarely yielding limeAlexander, in crossing the mountain-range which Arrian stone), in which, though unequally, and in degrees varying calls Caucasus (iii. 28, 10), and which is the same range that with locality, slaty cleavage tends to be developed. Organic he afterwards mentions under the name of Paropamisus (v. life has left traces in this series of muddy sediments both 5, 3), met with the Silphium. Arrian says, on the authority of vegetable and animal origin; in the lower and older parts of Aristobulus, 'In this part of the Caucasus nothing grows very sparingly, in the upper parts abundantly. If, with except pines and Silphium, but the country was populous, Professor Sedgwick and Mr. Murchison, we take the series and fed many sheep and cattle, for the sheep are very fond of these rocks as they appear in Wales and Cumberland, of the silphium. If a sheep should perceive the silphium namelyfrom a distance, it runs to it, and feeds on the flower, and

Silurian, or upper group ; digs up the root and eats that also. For this reason in Cy

Cambrian, or middle group; rene they drive the sheep as far as possible from the spois

Cumbrian, or lower group ; where the silphium grows, and some even fence in such we shall find in the mineral characters of these groups places to prevent the sheep from entering them, if they in the countries named, some diagnostic marks of importshould approach; for the silphium is worth a good deal to ance, but they vanish or become equivocal in other regions. the Cyrenwans.'' Burnes, in crossing the Hindu Koosh, ani In like manner the organic contents seem, in the countries seeing both the men and cattle eating the young parts of named, to be definitely arranged in zones, so as to mark the assafretida plant, supposed that it must be the silphium successive periods there: no organic remains are known in of Arrian. But as this author describes the country where the Cumbrian rocks; they are rare, and confined to a few the silphium grows as abounding in catile, Dr. Royle had layers, in the Cambrian deposits ; and are very plentiful concluded that the Prangos of Mr. Moorcroft was the sil, and general in the Silurian group. The districts in which phium alluded to, and which is much fed on by sheep and these peculiarities occur are probably more wide and scatcatile in the present day in Tibet. Mr. Vigne, when tra-tered farther asunder than those in which the original relling in these regions, came to the same conclusion. It is types of mineral structure prevail; but yet it is evident probable therefore that both plants, being umbelliferous, that they are limited in respect of geographical area, and and employed for the sarne purposes in nearly the same variable in regard to the distinctness and completeness of regions, may have contributed to form the accounts which the terms, even in districts not far removed from the centre are so brief in antient authors. (LASER; Prangos.] SI'LURES. (BRITANNIA.)

of investigation. Let any one who may desire proof of this

compare the argillaceous series of Ayrshire, Westmoreland, SILURIAN SYSTEM. One considerable group of the Pembrokeshire, Tyrone, or Waterford, in which Silurian fossiliferous primary strata, occurring in remarkable perfec- fossils occur, with the full and varied series of Shropshire, tion in Wales, especially in the eastern and some of the the Berwyn, and Snowdon. southern districts, and in some of the adjoining English Under these circumstances of difficulty in regard to the counties, is thus named by Mr. Murchison in a very splendid right general view of the antient fossiliferous strata, we work, the fruit of his long investigation of this part of the must consider the series of Silurian rocks and fossils not as series of British strata. Under this title we propose to ar

the type of this enormous sequence of mineral and organic range some general views of the present state of our know- phenomena, but as one, and perhaps the richest of all the ledge regarding the history of the lower Palæozoic strata. local physical combinations of that antient period, and em[GEOLOGY; PRIMARY STRATA; Palæozoic Rocks; Sali- ploy it as a general term of comparison for reducing to FEROUS SYSTEM.)

order and place many detached and difficult districts in When Mr. Murchison commenced his researches in which the 'strata hare local, peculiar, and perhaps excepShropshire and Wales (1831), the principal knowledge we tional aspects. possessed of the succession of the older stratified rocks of Mr. Murchison arranges the Silurian strata in groups, as Britain, then commonly called grauwacké and transition follows; in a descending order :formations, was based on the still incompletely published labours of Sedgwick in Wales and the district of the Eng

Divisions. lish lakes; and so little was known of their fossil contents,

Upper Ludlow rocks that it is believed the first definite notice of this kind was

Ludlow rocks

1500 Upper

Aymestry limestone

Lower Ludlow rocks contained in Mr. Phillips's description of a group of slate- Silurians rocks in the vicinity of Kirby Lonsdale. (Geol. Trans.,

Wenlock rocks 1827.) Now, in consequence principally of the develop

1000

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Wenlock shale ment given to this subject by the appearance of the Silurian researches of Mr. Murchison, and other works to which it

Lower Caradoc rocks

very

variable nearly the whole series of mineral depositions and organic We shall present a very brief analysis of some of their combinations of which the ocean was antiently the theatre, characters. from the period of the mica schists to the termination of

Upper Ludlow Rocks. the carboniferous æra.

Mineral Character. --Greyish, argillaceous, or calcareous In this survey, the Silurian strata form a very conspicuous sandstones, very slightly micaceous, decomposing to ashen and interesting portion, and in the district from which the or rusty-brown colour. type was originally drawn they appear within distinct and Structure.—Mostly laminated, parallel to the stratifica. definite limits which seem to insulate them from the older tion, with joints considerably symmetrical, nearly rectanguand new rocks, and to justify their claim to the rank of a lar to the plane of ihe beds, as near Ludlow. peculiar system; but in other districts phenomena appear Aspect of the Country.-A region rising from beneath

Formations.

Thickness

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The old red-sandstone, often to a considerable and rather , gimyona, 1; Mesomyona, 3; Brachiopoda, 53; Gasterocontinuous escarpinent, as near Usk and Ludlow.

poda, 7; Monothalamacea, 3; Polythalamacea, 6; CruisOrganic Contents.-Polypiaria, 2 ; Crinoidea rare; Con- iacea, 8; Doubtful, 2 (in all about 95 species). chifera Plagimyona rather plentiful, 10; Conchifera Meso Mineral Veins.-Green copper-ore (Malachite); thin myona, 1; Conchifera Brachiopoda, 15; Gasteropoda, 6; strings of galena ; and in the vicinity of trap true mineral Cephalopoda Monothalamacea, 3 ; Cephalopoda Polythala- veins occur. macea, 6; Crustacea, 5; Annelida?, i; Fishes, 7; Doubt Localities.—Caer Caradoc; May Hill; near Llandeilo. ful, 3 (in all about 58 species).

Llandeilo Flags.
Localities.—Ludlow ; vicinity of Usk.

Mineral Character.—Hard dark-coloured flags, some.
Aymestry Limestone.

times slightly micaceous, frequently calcareous.
Mineral Character.-Subcrystalline, argillaceous lime. Structure.—Thinly laminated, parallel to the stratifica-
stone, bluish-grey, or motiled, as near Aymestry.

tion, with some internal oblique cleavage. Structure. -- Irregularly laminated, or nodular; withi Aspect of the Country.--Not characteristic, the stratificross joints nearly rectangulated to the plane of stratifica- cation being commonly very highly inclined and the masses tion.

very thick. Aspect of the Country.-Often a slightly prominent ter Organic Contents.-Polypiaria, 4; Crinoidea rare ; Plarace on the woody steep escarpment of a hill, capped with gimyona, 1 ; Mesomyona?; Brachiopoda, 26 ; Gasteropoda, Upper Ludlow rocks, as near Ludlow.

3 ; Monothalamacea, 1 ; Polythalamacea, 1; Crustacea, 11 Organic Contents.-Polypiaria, 12; Crinoidea rare ; Pla- (in all about 47 species). gimyona, 6; Mesomyona, 2; Brachiopoda, 12; Gastero Mineral Veins.-Occur in the vicinity of trap, as in the poda, 9; Monothalamacea, 1; Polythalamacea, 4; Crusta- Shelve and Corndon district. cea, 3 (in all about 49 species).

Localities.- Near Built; Llandeilo; Pembrokeshire. Localities.—Aymestry; Sedgeley near Dudley, &c. Pyrogenous rocks are associated with the Silurian strata Lower Ludlow Rocks.

in many situations—as the Caradoc Hills, where compact Mineral Character.- Argillaceous (called Mudstone'), felspar predominates—the Wrekin and Lilleshall Hill, chalight-grey, dark-grey, or black, but weathering to ashen racterised by sienitic rocks-Corndon, full of greenstone. hues, as in the Wigmore Valley.

Alterations of stratified rocks by the contact of igneous Structure.—Partially taggy, in places the lamination is rocks are common in the Caradoc, Stiperstones, &c. The uneven and nodular. In the lower parts, nodules of black trap rocks near Welshpool are in places columnar; the limestone in lines of stratification.

Breiddyn Hills are mostly greenstone, and yield elongated Aspect of the Country:-Toward the base of the steep dykes in a north-east direction, which traverse the new redescarpment of a hill, which may contain the whole Ludlow sandstone. Mineral veins (yielding lead-ore) are plentiful formation, as in the Wigmore Valley.

in Lower Silurian rocks, in the Shelve district, adjacent to Organic Contents.- Polypiaria, 9 ; Crinoidea rare; Pla- the trap rocks of Corndon, and the altered sandstones of the gimyona, 8; Mesomyona, 2; Brachiopoda, 19; Gastero. Stipersiones. 'In a plan of Mr. More's of Linley Hall, the poda, 7; Monothalamacea ?; Polythalamacea, 27; Crus chief proprietor of this district, upwards of 24 are laid down tacea, 3 ; Annelida, 1; Fishes, 1; Doubtful, 2 (in all about in the district of Shelve alone, excluding the tracts around 79 species).

the Bog and Penally: so that, comprehending the principal Localities.-Ludlow; Usk.

portion of the mining-ground, we may say that it contains Wenlock Limestone.

upwards of 30 metalliferous veins which have been profitaMineral Character.-Grey, bluish, or pinkish crystalline bly worked.' (Murchison, Sil. Syst., p. 282.) and subcrystalline limestone, arranged in strata of concre Volcanic grits, composed of materials derived from igneous tionary aspect, separated by much argillaceous matter. action, and subsequently arranged in water, ale mentioned

Structure.-As above stated, concretionary in detail, but by M. Murchison rather frequently. In the Shelve district stratified on a large scale with considerable persistence of they are traversed by lead veins; in the Caradoc Hills, they the parts. The concretionary structure most remarkable at abound, and were noticed as 'allied to greenstone' in the top and bottom.

Wrekin by Mr. A. Aikin. They contain organic remains in Aspect of the Country:-- Usually a prominent or terrace- several places, as near the Corndon Hills. like escarpment, where the beds dip moderately; rising to On reviewing the series of strala comprised in the Siluinsulated hills, where contortions prevail, as near Ludlow, rian System, in the vicinity of Ludlow, Usk, Llandeilo, or Wenlock, Malvern Hills.

Denbighshire, we see them to form in reality one closely Organic Contents.—Polypiaria, 53 ; Crinoidea, 14; Pla- associated sequence of oceanic deposiis-apparently accugimyona ?; Mesomyona, 1; Brachiopoda, 28; Gasteropoda, mulated with little local disturbance and very slight admix8; Monothalamacea, 2; Polythalamacea, 9; Crustacea, 14 ; ture of organic exuviæ from the land. Volcanic eruptions Annelida, 1; Doubtful, 2 (in all about 132 species). appear to have rather varied than greatly disturbed this Localities.—Dudley: Wenlock; pear Usk.

system of operations, though it is evident ihey contributed Wenlock Shale.

no small part of the granular materials of the principally Mineral Character.-Dull argillaceons shale, with concre- sedimentary strata. The formation of limestone is local :tions of impure argillaceous limestone, much analogous to where coral prevailed, we find the Aymestry and Wenlock the argillaceous Ludlow rocks.

limestones, and even the calcareous parts of the Landeilo Structure.— Laminated, with spheroidal calcareous con- rocks, to be in a great degree filled with coral. The Brachio. cretions, especially toward the base.

pod shell · Pentainerus’ fills some whole beds of limesione Aspect of the Country.-- Owing to the wasting of the inear Aymestry), and where it is deficient the limestone middle beds, this shaly mass is often :he line of a valley. also fails, as in the district of Usk. In their course from

Organic Contents.— Polypiaria, 18; Crinoidea rare ; Pla- Shropshire, north ward to Denbighshire, Mr. Bowman (Regiinyona, ! ; Mesomyona? ; Brachiopo la, 33 ; Gasteropoda, ports of the British Association for 1840-41) has found ihe 4; Monothalamacea ?; Polythalamacea, 5 ; Crustacea, 2 ; general type of the Silurian rocks to vary, and the line of Annelida?; Doubtful, 2 (in all about 65 species). There distinction between it and the slaty strata below to be exare marine plants in this deposit, and we have seen them treinely obscure; and similar observations are recorded by of a vermilion colour.

M. Murchison in the account which he gives of these rocks Locality.-- Wigmore Valley.

in Caermarthenshire and Pembrokeshire. Caradoc Sandstone.

Mineral character alone will scarcely suffice, anywhere, Mineral Character.—Sandstones of various colours, more for any but an arbitrary (and therefore unsatisfactory) or less micaceous, sometimes quartzose or conglomeritic, boundary-line between the Silurian and Cambrian deposiis. with thin courses of impure limestone, especially in the It is extremely probable, perhaps we may say it is already upper part. (Where altered by igneous action, this sand- proved, that no distinction of higher value can be found on stone becomes a sort of quartz rock.)

comparing the organic remains of these groups. In Snowdon Structure.- Usually laminated. Where altered by heat, (supposed to be very low in the Cambrian series of rocks) the stratification is nearly or quite lost.

are shells and corals, which are perhaps the same, but cer Aspect of the Country.- Very characteristic where the tainly are congeneric with and very similar 10 Silurian strata are indurated by vicinity of trap-rocks: the quartz- fossils; and there is really as great (if not greater) difference ose masses then assuming very picturesque forms.

between the Llandeilo and Wenlock rocks, in regard to Organic Contents. -Polypiaria, 12; Crinoidea rare; Pla- ) fossils, than between the Silurian and Cambrian strata.

Genera.

6

8

If we turn to other districts where Silurian fossils occur | Crinoidea, and Crustacea are most numerous in the principlentifully (North America, Ireland, Norway), the result pal calcareous rock, Wenlock limestone; Brachiopoda are appears the same. There is apparently only one great series most plentiful Caradoc sandstone; Cephalopoda, in the of organic combinations distinguishable among The fossili- Wenlock shale; fishes, in the upper Ludlow rock. ferous strata anterior to the old red-sandstone ara, and it Mr. Murchison gives the following general recapitulation was with a perception of this important truth that Mr. Mur- of organic remains in these strata : chison once proposed for the Silurian strata the title of Pro.

Species tozoic. If instead of this we employ Palæozoic (as suggested Pisces

15

24 by Sedgwick), and adopt the general view advocated in this

Crustacea

10

37 work (PALÆOZOIC ; SALIFEROUS SYSTEM), we shall rank all

Annelida

5 the fossiliferous strata of the Cumbrian, Cambrian, and Silu Mollusca (Heteropoda*) 1

11 rian groups as Lower Palæozoic Strata.

(Cephalopoda)

6

41 The lower arbitrary boundary of the Silurian strata being

(Gasteropoda

13

34 thus softened or erased, we may regard its upper surface as Conchifera (Brachiopoda)

107 only locally more definite. Certainly in all the region

(Monomyaria)

1

6 around Wales the separation of the Silurian and old red

(Dimyaria)

10

21 deposits is somewhat sudilen; the colour changes from grey Crinoidea

5

14 to red; the dull mudstones become micaceous sandstones;

Polypiaria

35

65 the richly fossiliferous Upper Ludlow loses its character in

Doubtful

6

9 unprolific red marls and grits. What few fossils do occur in these overlaid strata (except near the very bottom) are

115

375 of quite other types of organization. But these are local truths, depending mainly on the introduction of new sedi SILU'RIDÆ, a family of fishes of the order Malacopments poisonous to marine invertebral life; and as these terygii, placed by Cuvier, in his · Règne Animal,' between sediments are very local, we may find in other countries the Esocidæ, or Pike tribe, and the Salmonidæ, or family groups of strata newer than the Silurian, older than the of the Salmons; but in the 'Histoire Naturelle des Pois. Carboniferous, with fussils intermediate in character and sons, the present group commences the Malacopterygii. combination to both.

The family Siluridæ constitutes a very extensive section of This expectation is in course of fulfilment, but it is not fishes, the species of which are for the most part confined to yet fully satisfied. In Devonshire, the Rhine Valley, the the fresh waters of warm climates. No group perhaps preEifel, we find numerous assemblages of such Middle Palæo

sents greater diversity of form than the Silurians, and their zoic fossils, but they do not by any means fill the whole in- habits are equally interesting. Their most obvious external terval between the Silurian and Carboniferous types; nor

characters are, the want of true scales; the skin is generally have we seen in collections from North America, Australia, naked, but in parts protected by large bony plates; the the Hartz, Brittany, or Russia, all that is desired to fill the foremost ray of the dorsal and pectoral fins almost always void. Ever alive to this most interesting inquiry, the author consists of a strong bony ray, often serrated either in front of the 'Silurian System' is perhaps at this moment adding

or behind, or on both sides. These fishes moreover frevaluable facts concerning it, the fruit of his continued quently are furnished with a small adipose fin on the hinder researches in Russia ; and we believe that by further exami- part of the back, as in the Salmonide. The mouth is alnation of the lower strata of the Rhine Valley, and the most always provided with barbules. Harz, some additional data may be gathered.

The genus Silurus, as now restricted, is distinguished by At present the most important of the discoveries which the dorsal fin being very small, without any distinct spine, (however incompletely) represent a Middle Pulæozoic and situated on the fore part of the back; the anal fin is of Period, have been in Devonshire and Cornwall, in the great length, extending along the whole belly of the fish, Fichtelgebirge, and in the Eifel and Rhine Valley. The and sometimes joining the tail-fin; the maxillaries and inprincipal of these, at least in regard to the analogies which it termaxillaries are furnished with small thick-set curved offers io the strata of earlier and more recent date, is the teeth, and there is a band of similar teeth on the vomer. district of Devon and Cornwall; from which ten years ago

The species of this genus are confined to the old world; only a small number of fossil species was known, but which the only known European species is the Silurus glanis has now yielded to numerous inquirers fully 300 distinct and (Linn.), a fish of very large size, which is found in the lakes recognisable forms. Of these, according to Mr. Lonsdale, of Switzerland, in the Danube, the Elbe, and all the rivers who gives (Geol. Trans. 1840) a table of the species which

of Hungary. In Prussia and Sweden it is also found. he examined, and to Mr. Murchison and Professor Sedy fishes of this country. It has however, says Mr. Yarrell

,

The Šilurus glanis is introduced in several works on the wick, who enumerate 128 species, a few of these species are found in the Silurian and a few in the Carboniferous rocks. been suspected that ihe so-called Silurus, supposed to have Professor Phillips, in his recent work (Palæozoic Fossils of been found formerly in some of the Scoilish rivers, might Devon and Cornwall), discusses the relations of 275 species,

have been the burbot. and arrives at the conclusion that both by numerical valuations feet in length, and is said to weigh three hundred pounds

Cuvier states that this fish is sometimes upwards of six of the general combinations of groups of invertebrata, and (French). The body is elongated, and has the hinder part hy specific analogies, the conclusion of the intermediate of the Devon and Cornwall strata is confirmed. As the compressed, but towards the head its width gradually indifferences of the Devonian and Silurian fossils are very colour is dark-green above, of a pale-green below the laterai

creases, and the head itself is depressed and large; its much greater than those between the Silurian and Cambrian fossils, it appears probable that the boundary assumed by line, and yellowish on the belly, and the whole body is MIr. Murchison for the upper termination of the Silurian covered with dark spots; six barbules surround ils neath, Eroup may remain with but slight alteration. One change and two of these, which have their origin (one on each side) contemplated by the author himself we should be glad io just above the angle of the mouth, are very long. see adopted :—there are some fossiliferous bands placed by

Mr. Yarrell observes, 'The Silurus is represented as slugMr. Murchison near the base of the old red system, which gish in its habits, and a slow swimmer, taking its prey by would better go to the Silurian ranks, since, in respect of lying in wait for it, in a manner somewhat similar to the the shells which they contain and their mineral composition, Angler, Lophius ; hiding itself in holes or soft mud, and they are scarcely disiinguishable from Silurian straia. apparently depending upon the accidental approach of fishes On considering the distribution of organic remains in

or oiher animals, of which its long and numerous barbules the successive stages of the Silurian rocks, it is evident may be at the same time the source of attraction to the that the greatest variety of species occurs in the lower part its formidable size, it can have but few enemies in the fresh

victims, and the means of warning to the devourer. From of the upper and towards the upper part of the lower SiluMan rocks. In other words, the conditions favou able to water; and from them, its dark colour, in addition to its organic life in the sea were in the earliest period consider-habit of secreting itself either in holes or soft mud, would able; they arrived at a maximum in the middle part of the be a suflicient security: In spring, the male and female period, in the Caradoc sandstone, the Wenlock Shale and may be seen together, about the middle of the day, near the the Wenlock limestone, and still continued considerable till banks or edges of the water, but scon return to their usual the Silurian depositions ceased, and were replaced by old retreats. The ova, when deposited, are green; and the red-sandstone nearly devoid of organic remains. Polypiaria, These, in the preceding paragraphs, we have called Monothalamacea.

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young are excluded between the sixteenth and nineteenth chiostegous rays are twelve in number; the teeth are longer days.

and less abundant ihan usual in the Siluridæ. The only • The flesh of the Silurus is white, fat, and agreeable to species known (Silundia Gangetica, Cur. and Val.; Pimemany persons as food, particularly the part of the fish near the lodus Silundia of Hamillon) is said to be very common at tail; but on account of its being luscious, soft, and difficult the mouth of the Ganges, and to be much esteemed for to digest, it is not recommended to those who have weak food. stomachs. In the northern countries of Europe the flesh Genus Arius, Cuv. and Val.- Contains many species of is preserved by drying, and the fat is used as lard.' Siluridæ, allied to the Bagri, but distinguislied by their

It

appears by some statements in the ‘Histoire Naturelle palatine teeth forming two distinct and widely separated des Poissons,'ihat the present fish is so voracious, that it masses. In some species the teeth are minute and denise, has been known, in several instances, to devour children; like the pile on velvet, or like the teeth of a carding machine, and in one instance the body of a woman was found in one and in others the palate is furnished with teeth in the of these fishes.

rounded form of paving-stones, instead of having them Several examples of the restricted genus Silurus are pointed. Species of this genus are found in the tropical found in Asia.

portions of both continents, and also in North America. Cuvier separates from the typical Silurı, as a genus, the Genus Auchenipterus, Cuv. and Val.--May be distinSilurus mystus of Linnæus, and some others, on account of guished from other genera which possess the adipose fin by the compressed form of the body, and the dorsal fin having ihe small size of the head, the very minute size of the teeth, a strong bony spine in front, which is denticulated on the and there being five branchiostegous rays. It evinces an hinder margin. The body is deepest near the middle, but affinity with Pimelodus in having no palatine teeth, and in tapers somewhat suddenly towards the extremities. The the number and form of the maxillary barbules. The first head is small and depressed, and the eyes are placed low dorsal is situated very forward, a circumstance which sugdown.

gested the generic name. The bony shield which covers The species upon which Cuvier founds this genus--to the upper surface of the head is, in the fishes of this genus, which he applies the name Schilbe-are found in the Nile, united by a suture with the dilated bony nuchal plates. All but there are others described in this author's great work the known species are from the tropical portions of South on fishes, one of which is found at Senegal and another in America. India.

Genus Trachelyopterus.--The genus is founded by Genus Cetopsis.- This genus is founded by Agassiz on MM. Cuvier and Valenciennes, upon a small Silurian from certain species found in Brazil, which in their affinities ap. Cayenne, in which there is no adipose fin; the teeth are proach the genus Silurus, but are distinguished by the ex- fine, like the pile of velvet, and the palate is destitute of tremely small size of their eyes.*

teeth ; the barbules are six in number. The head is someGenus Bagrus, Cuvier.—The species of this genus are what short, and protected by a stout bony shield, which is distinguished from those of the genus Silurus, as restricted, united almost immediately with the dorsal on account of by their possessing an adipose fin on the hinder part of the the shortness of the interparietal plate, and almost rudimenback. The body is naked—that is, unprovided with bony tary state of the chevron, placed generally in front of the plates and the mouth is provided with barbules, the num- spiny rays of the dorsal fin; the pectoral fins are inserted ber of which, varying in different species, has been selected as it were under the throat. for the minor divisions of the group. Numerous species Genus Hypophthalmus (Spix), Cuv. and Val.—This genus are found in the Indian and African rivers.

is com posed of but few species, and these are from the tropi. Genus Pimelodus, Lacép.-Differs from Bagrus in having cal portions of South America. The principal characters no teeih on the vomer; the palatines however are often pro :-Mouth destitute of teeth ; eyes placed very low down vided with teeth. The species vary much in the number of near the angle of the mouth; branchiostegous rays fourteen their barbules, and in the form of the head, which is often in number; body furnished with an adipose fin. protected by a bony plate, and a large bony plate is situated Genus Ageneiosus (Lacépède), Cuv. and Val.--This genus between that on the head and the dorsal spine; similar is thus characterised in the 'Règne Animal:'-Characters the bony plates on the head however are observable in many of same as in Pimelodus, excepting that there are no barbules the species of the preceding genus. The species of Pime- properly so called. In some, the maxillary bone, instead of lodus are very numerous, and are found both in the Old and being prolonged into a fleshy and flexible barbule, assumes New World. Numerous species are described from North the form of a projecting denticulated born. In others this America, others are found in South America, and the rivers bone does not project, but is concealed under the skin; the of India also furnish numerous examples.

dorsal and pectoral spines are but little apparent. All the Genus Phructocephalus, Agassiz. - This genus contains species are from South America. but one species, an inhabitant of the Brazils; its generic Genus Synodontis, Cuv.-This genus is composed of distinction consists in its possessing some incomplete osseous Silurians found in the Nile and Senegal, which have an rays enchased in the upper margiu of the adipose fin. The adipose fin, the muzzle narrow, and terminated by an head is depressed and covered by a deeply sculptured bony ethmoid which supports two small intermaxillary bones plate; a second bony plate, of a transverse oval form, is armed with bristle-like teeth; the lower jaw composed of situated in front of the first dorsal fin. The branchioste- two short and slender rami, bearing in front a mass of teeth gous rays are nine in number, and the mouth is provided which are in the form of very slender laminæ and closely with six barbules.

packed-each of these teeth is attached to the jaw by a Genus Platystoma, Agassiz, is composed of several South flexible and very slender stalk. The stout bony plate which American species of Siluridæ which have the muzzle de- covers the head is joined to the nuchal plate, and ihis extends pressed, and are remarkable for the great number of their to the first spine of the dorsal fin, which is of very large size, branchiostegous rays, which amount in some to fifteen in and in this respect resembles the first spine of the pectoral number. Some of the species attain a large size, there fins. The inferior barbules, and sometimes the maxillary being specimens in the Paris Museum as much as five feet barbules, have small lateral branches. in length, and they bave been seen of still greater bulk. Genus Doras, Lacépède.- The species of this genus are

Genus Galeichthys, Cuv. and Val.—This genus is nearly distinguished by the lateral line being armed with bony allied to Bagrus, but distinguished by the head being round plates, which are carinated, and terminate in a spine. They and unprotected by any distinct bony plate: the branchios- have a second adipose dorsal fin, and the foremost spine of tegous rays are six in number. Some possess six barbules, the pectoral and anterior dorsal fins is very large and deeply and others have four. One species is found at the Cape serrated. Osseous plates cover the upper surface of the of Good Hope, a second is said to be found both in North head and extend to the dorsal fin, and the humoral bone is America and at Rio Janeiro; several species occur in produced backwards and pointed. Brazil, and the Ganges also furnishes a species of the pre- Naturelle des Poissons," as the most powerfully armed of

These may be regarded, say the authors of the Histoire sent genus.

Genus Silundia, Cuv. and Val.- This genus is founded all the Siluridæ ; thus the Spanish colonists in South upon a fish from the Ganges, which has the head small and America have given to them the name Mata-caïmun (or smooth, a very small adipose fin, and a long anal fin. It Crocodile-killer), because it often happens that when they has but two barbules, and they are very small; the bran- are swallowed by these large reptiles, the æsophagus and

• See the part on Jehthyology of the 'Voyage of MM, Spix aud Mar- pharynx of those animals are so lacerated by the spines of Una

The Silurus as to cause death. Strabo also (p. 824, Casaub.

are:

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