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its life, either in the water by means of branchiæ, or in the each a groove for the lodgment of the posterior point of two air by means of lungs. This conclusion rested upon that slender bones, which proceed beside each other to the end solid basis which has given such value-a value daily be- of the muzzle. At their sides are attached two other bonus, coming more appreciated-to the views of this great zoolo- which are slender and pointed backwards, and which degist,- his personal observations made on the osteology and scend and widen far in order to raise the anterior edge ou splanchnology of the animal.
the jaw. Cuvier takes the first for the nasal bones, and the Dr. Garden had, in his correspondence with Linnæus others for intermaxillary bones. These last are toothless, and Ellis, come to the same conclusion from other evi- but their edge is trenchant, and furnished, when the animal *dence. Dr. Garden had observed the animal from the length is alive or well preserved, as well as the edges of the lower of four inches to that of three feet and a half; he had jaw, with a sheath which is nearly horny, is easily detached satisfied himself that in the whole province there was not, from the gum, and has its analogue in the tadpoles of the with the exception of the alligator, any Saurian or Sala- frogs. (SALAMANDRIDÆ, vol. xx., p. 328.) Between them, mander which exceeded six or seven inches in length, and at ihe end of the osseous muzzle, is an aperture, but not he had convinced himself that it was oviparous, and that it that of the nostrils. In the recent animal it is closed, and propagated without losing its branchiæ.
the nostril is pierced on each side on the outside of the inIn 1766 Hunter, as we shall presently see, declared the termaxillary bone. In the crocodile the intermaxillary adŞiren to be a complete form, on the most satisfactory evi- heres to the external side of the nasal bone, and all the dence: the specimens dissected by him were brought from reptiles, except the crocodile, have the nostril on the outSou Carolina in 1758.
side of the ascending apophysis of the intermaxillary bone; That the Siren is a perfect animal belonging to the pe- but the peculiarity in the Siren is, that the intermaxillary rennibranchiate batrachians is now admitted by all zoo ascending to the irontal bone entirely separates i he nasal logists. Cuvier indeed remarks (Règne Animal), that bone from the frame of the external nostril
. The maxillary the branchiæ of Siren intermedia and Siren striata have bone excludes the nasal in the same way in the chameleon. been regarded as not participating in their respiration, and A very small bone, suspended in the flesh below the exterthat in consequence Mr. J. E. Gray has formed them into nal nostril, and without any tooth, is the sole perceptible the genus Pseudobranchus. Cuvier however adds, that it vestige of the maxillary bone. The cavity of the nostril is is, nevertheless, not difficult to see on their lower surface covered below with a simple ligamentous membrane. The folds and a vascular apparatus, the use of which does not internal nostril is situated on each side, near the commisappear doubtful to him; and that M. Leconte has satisfac-sure of the lips, between the lip and the palatine teeth. All torily demonstrated that both these species, as well as Siren the lower part of the cranium and the face is composed of lucertina, are perfect animals.
a large and wide sphenoïd, which extends from the occipital Cuvier remarks that the Siren should be judged of not hole to the intermaxillaries. The sides of the cranium, in after Amphiuma, but from itself
. He accordingly, procured the orbital region and the front of the temporal bone, are some sirens, and saw an osteology so finished and so firm, closed by a single bone, in which are pierced, forward, the that it was impossible to believe that they were not adult. olfactory aperture; farther back, the optic hole, and anThe branchiæ of these individuals were perfectly entire, other for the first branch of the fifth pair, and probably for and their lungs completely developed, and rich in well- the small nerves of the eye. The inferior surface of this filled vessels. No doubt therefore existed in his mind that lateral bone forms part of the palate at the sides of the the animals used both.
sphenoïd bone. It is plain that it performs the functions of He observes, that it had been objected that it would be the orbital part of the sphenoid bone, or what has been impossible for these animals to respire air without ribs or called the anterior sphenoïd, and that it fulfils in part those diaphragm; and without the power possessed by the tor of the ethmoïd. Between it and the petrous bone is a great toises and frogs to cause it to enter by the nostrils, in order membranous space, in which is pierced the hole for the rest that, so to speak, it might be swallowed, because the nostrils of the fifth pair of nerves. The petrous bone and the lateral of the Sirens do not lead into the mouth, and the branchial occipital bone are perfectly distinct. It is in the petrous apertures must let it escape. But his own observations made bone only that the fenestra ovalis is pierced, or rather cut upon well-preserved individuals showed Cuvier that the nos- out, but the lower part of its frame is, nevertheless, comtrils in the siren do conumunicate with the mouth by a hole pleted by the lateral occipital and the sphenoïd. Its aperpierced, as in the Proteus, between the lip and the palatal | ture, which is large, is directed a little downwards. 'In bone which carries the teeth. The membranous opercula the fresh state it is closed by a cartilaginous plate siof their branchiæ are muscular internally, and capable of milar to that in the Salamander. There is only a single hermetically sealing the apertures; then it is very easy for tympanic bone fitted obliquely by its posterior stem on the siren, by dilating its throat, to introduce the air into the superior surface of the petrous bone, and enlarging bethe mouth, and to force it afterwards, by contracting the low nearly like a trumpet, in order to furnish a large facet throat, into its larynx. Even without this structure of the to the lower jaw. Cuvier found neither mastoïdian, pterynostrils, the animal could produce the same effect by open- goïdian, jugal, superior occipital, nor basilary bone, and he ing its lips a little : a theory which Cuvier applies to the Pro- remarks that the occurrence of the two last is impossible, teus as well as the Siren.
when the position of the suture, which separates the lateral The simultaneous existence, observes the same author, of occipital bones, is considered. To the palate, under the ana larynx and a trachea with a branchial apparatus not only terior and lateral part of the sphenoïd and orbital bones, are permanent, but perfectly ossified in many of its parts, is fitted two delicate plates beset with hooked teeth. They also worthy of especial attention, and proves, as is evident may be taken for the vestiges of vomers and of palatines, or, in the frogs and salamanders, that the branchial apparatus if it be preferred, of palatines and pterygoïdians; but Cuis no other than a more complicated os hyoides, and not vier did not find sufficiently marked characters to warrant a combination of pieces proceeding from the sternum and giving them those names. The first, which is the largest, larynx. He adds, that it is to the salamanders that the has six or seven oblique rows of pointed teeth, making a sirens approach most nearly by the structure of the head, kind of wool-card. Those of the middle have each twelve although neither the general form nor the proportions of teeth; the anterior and posterior ones have less. The the parts have so near similarity.
second plate has four rows of similar teeth, each row conHaving thus given a general view of the conformation of sisting of from five to six. this extraordinary animal, we proceed to a sketch of the The lower jaw of the Siren is composed of four bones on details of its
each side; one of which forms the symphysis and the trenchORGANIZATION.
ant border of the jaw, which it invests externally up to near Skeleton.—The skull of the siren is narrowed in front by its posterior extremity. One cannot, Cuvier observes, avoid reason of the excessive reduction of the maxillary bones, taking it for the analogue of the dental portion, but it is not which consist only of a very small osseous point. Behind the portion which carries the teeth, and it has only its there is a strong occipital crest on the parietal and petrous trenchant edge invested in the fresh animal with a horny bones. The pieces which form the lower jaw, instead of covering,' analogous to that which forms the edge opposed being transverse like the branches of a cross, are directed to the upper jaw. The posterior extremity of this trenchobliquely forwards. The parietal bones occupy the greatest ant edge, more elevated than the rest of the border of the portion of the upper part of the cranium. They have each bone, serves for the coronoïd apophysis. The second bone in front a point, expanding so as to lodge between them forms the greatest portion of the internal surface and the the posterior part of ihe principal frontal bones, which have posterior angle, and carries, above, the third, which is tho P. C., No. 1366.
articular tubercle. The fourth is a delicate and narrow | bifurcated, and ne branches go to terminate on the articular laminu which performs the office of the opercular bone, and posterior apophysis. Their very wide transverse apophyscs covers, on the internal surface, a vacancy left between the are composed of two laminæ united at their posterior border iwo first. The whole of this bone is beset with small up to their common point; the upper, which is oblique, pointed teeth disposed quincuncially like those of the palatal coming from below the anterior articular apophysis and plates.
from below the neighbouring part of the lateral crest, the The os hyoides of the Siren is an os hyoides of the larva lower coming from the sides of the body, 10 which it adof a Salamander or of the Axolotl, but very much ossified heres by a horizontal line. The body below is also comin many of its parts. The suspensory branch or anterior pressed into a sharp ridge (arête). horn is a bone stouter and longer than the humerus, dılated In the vertebrce which carry the ribs, the upper lamina at its two ends, narrowed in its middle, and suspended to of the transverse apupbysis is but little marked, and the the cranium by a ligament. The first unequal piece is also point is stout and divided into two lobes for the two tubercles a very hard bone dilated anteriorly, compressed posteriorly, of the rib, as in the salamanders. Cuvier only found eight of and narrowed in its middle. The second unequal piece is a these vestiges of ribs on each side, commencing from the pedicle, which is divided behind into many radiating apo. second vertebra. The two last have the head simple. At physes: the whole of this, again, is very bony, and the two the tail, the transverse apophyses, which have already belateral branches are equally so. The first, which is the come rather small, promptly disappear : the articular apostoutest, carries the first arch of the branchiæ; the second, physes diminish also by degrees. The body of the tertebra which is more slender, carries the three others. These iakes a very compressed form, and gives below two small gill-arches are not ossified, but always remain cartilaginous, laminæ, which intercept a canal for the vessels, like the as in the Axolotl, and are, like those of the Axolotl, denti- chevron bones in the lizards. lated. They are united by ligaments at their external extremity, which a ligainent attaches also to the root of the anterior horn., The same pieces, or very nearly the same, may be seen in the Proteus.
The shoulder-blade of the Siren is slender, nearly cylin. drical, narrowed in its middle, and augmented, on the spinal side, by a cartilaginous lamina. The clavicle and the coracóid are represented by two cartilaginous lobes, one directed forwards, the other much wider, proceeding upon the breast and crossing upon that of the opposite side. In the external border of this coracoïd cartilage, near and a little behind the articular fossa, is a bony semilunar lamina which is the sole representative of the bony coracord: but there is nothing similar for the clavicle. The humerus compressed laterally above, from before backwards below, and narrowed in its middle, has its extremities cartilaginous. It is the same with the two bones of tbe fore arm, both rather slender, and the internal bone or radius widened below. The bones of the carpus remain cartilaginous.
Each of the four fingers has a metacarpian and two phalanges only.
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Entire skeleton of Sirer lacertina. YonT89! berlojohod 2016
Respiratory Organs.-John Hunter in 1766 gave the folcanining to bugil
lowing accurate and interesting description of the two-fold
respiratory apparatus of the Siren :-"On the posterior and 3101784 0 27910EAN ban on
lateral parts of the mouth are three openings on each side ; Jelta diri
SIT SEO ratli gun these are similar to the slits of the gills in fish, but the pare.t1991 helik OT Sindo 2
titions do not resemble gills on their outer edges, for they Anterior portion of the skeleton of Siren lacertina. a, dorsal vertebra sceu bave not the comb-like structure. Above and close to the behind; b, the same seen before.
extremity of each of these openings, externally, so many There is no vestige of a pelvis, nor of any posterior extre- processes arise, the anterior the smallest, the posterior the mity, either osseous or cartilaginous.
jongest; their interior and inferior edges and extremity are Cuvier did not find in a large individual more than forty- serrated, or formed into fimbriæ : these processes fold down three vertebræ in the trunk and forty-four in the tail: but and cover the slits externally, and would seem to answer the the individual which he described in 1807 had three more. purposes of the comb-like part of the gill in fish. At These vertebræ, all perfectly ossified and complete, do not the root of the tongue, nearly as far back as these openings resemble in his opinion those of any of the reptiles of which reach, the trachea begins, much in the same manner as in he had previously treated, nor indeed of any other animal. birds. It passes backwards above the heart, and there Their bodies have their two articular faces hollow and united divides into two branches, one going to each lobe of the by a cartilage in the form of a double cone, as in the fishes. lungs. The lungs are two long bags, one on each s'de; Their articular apophyses are horizontal, and the posterior which begin just behind the heart, and pass back through apophyses of one vertebra lie on the anterior apophyses of the whole length of the abdomen, nearly as far as the anus. the other. A horizontal crest on each side goes from the They are largest in the middle, and honeycombed on their anterior to the posterior. In lieu of a spinous apophysis, internal surface through their whole length.' (Phil. Transa they have a vertical crest, which at half its length becomes lvi., 1766.)
In the Museum of the Royal College of Surgeons in Lon. "ular protuberance which projects into it from the dorsa: don this part of the organization is well illustrated. No. aspect. On the opposite side of the preparation the cra1062 presents a Siren lacertina, with the ventral parietes of nium and upper jaw are removed to show the apertures the abdomen removed, together with all the viscera, except leading from the mouth to the lungs and gills, the simulthe lungs, which have been distended with spirit. These taneous existence of which through life forms the chief cha. commence immediately below the pericardium, and extend racteristic of this tribe of truly amphibious repliles. No. 913 almost to the anus. A bristle is passed through the trachea, is the heart of a Siren. The auricle, consisting of two and the laryngeal orifice is exposed by the removal of the chambers, appears as one cavity externally. It is remarkcranium. The branchiæ are external, three on each side, able for its large size, its weak parietes, and the number of and suspended to four cartilaginous arches of the hyoïd bone. fimbriated follicular processes which it sends off, and The three internal branchial apertures of the left side may which gives it an appearance similar to the branchial be seen. No. 1063 exhibits the right side of the head of a divisions of the vena cava in the cephalopods. The larger specimen of Siren lacertina, showing the branchial ventricle is here seen to be slighily bild at the apex. arches and gills of that side. The first and fourth branchial The artery is membranons at its commencement. The bulb arches are fixed, the intermediate ones only being free. is here laid open to show the internal valvular projection. Their concave margins are provided, as in many fishes, with No. 913 A presents the heart and pericardium of a Siren small pointed processes, which lock into one another and lacertina, prepared to show the internal structure of the defend the branchial passages. The gills increase in size auricles and ventricle White brisiles pass from the veins of from the first to the third, which is suspendeil to both the the body into the right auricle, and black ones through the third and fourth arches. They are subdivided and fim- pulmonary veins into the left auricle. This is much smaller briated inferiorly, where the surface is most vascular: the than the right auricle, corresponding to the quantity of branchial arteries may be seen injected on the convex side blood which it receives. The pulmonary veins unite into a of the cartilaginous arches. The origin and subsequent common trunk,which seems to pass through the great sinus reunion of the branchial vessels to form the aorta are shown of the veins of the body, but it adheres to the parietes of in the preparation No. 914 (from which the present was that sinus by its posterior surface. Here Professor Owen taken), noticed below. No. 1064 is a portion of the lungs of remarks that it is probably this remarkable structure which led the same Siren, laid open to show the ramifications of the Hunter to suppose that the sinus was part of the pericardium, pulmonary artery, which form a vascular network upon the and that the venæ cavæ opened into it. The Professor then internal surface of this simple respiratory bag. (Catalogue, quotes Hunter's descriprion, above given, and adds, with vol. ii.)
truth, that all anatomists since Hunter's time bave conCirculating System.-John Hunter describes (1766) the curred in ascribing but one auricle to the heart of the Siren, heart of the siren as consisting of one auricle and ventricle. and that Cuvier regards this simple structure of the central • What answers,' says Hunter, to the inferior vena cava, organ of the circulation as common to the Batrachian order passes forwards above, but in a sulcus of the liver, and opens of reptiles. The outward form of the auricle, observes Mr. into a bag similar to the pericardium: this bag surrounds Owen, naturally suggests such an idea, and it is only in the heart and aorta as the pericardium does in other ani- favourable specimens that the true structure, as it is shown mals; from this there is an opening into a vein which lies in this preparation (made by him), can be made out. The above, and upon the left of the auricle, which vein seems to ventricle is connected to the pericardium, not only by the receive the blood from the lungs, gills, and head, is ana reflection of the serous layer from the bulbus arteriosus, but logous to the superior vena cava, and opens into the auricle by a duplicature of the same membrane, which passes from which is upon the left ventricle. The aorta goes out, pass the lower third of the posterior edge of the ventricle, and ing for a little way in a loose spiral turn, then becomes incloses the coronary vein ; this vein is continued from the straight, where it seems to be muscular: at this part the apex of the ventricle to the sinus. The muscular parietes of branches go off, between which there is a rising within the the ventricle are about a line in thickness, and of a loose area of the aorta like a bird's tongue, with its tip turned fascicular structure. The cavity is partially divided by a towards the heart. This account of ihe venæ cavæ opening rudimentary septum, which exiends from the apex hali into the cavity of the pericardium may appear incredible; way towards the base of the ventricle, and there terminates and it might be supposed that, in the natural state of the in a concave edge directed towards the orifice of the artery, parts, there is a canal of communication going from one The whole inner surface is reticulated by decussating carneæ cava to the other, which being broken or nipt through in the columnæ, one of which has been detached from its conact of catching or killing the animal, would give the ap. nection to the septum, which intervenes to the two auri. pearance above described. I can only say that the appear- cular apertures, and which supports the valvular structure ances were what have been described in three different sub- that closes them from within." The artery and bulbus arjects which I have dissected, and in all of them the pericar. teriosus are laid open, showing in the latter the remarkable dium was full of coagulated blood. But besides the small- valvular projection described by Hunter. In conclusion, ness of the subjects, it may be observed that they had been Professor Owen remarks that the vessels on the back part long preserved in spirits, which made them more unfit for of the talc, which supports the preparation, are, the inner anatomical inquiries. They had been in my possession above ones, the pulmonary arteries, the outer ones, the jugular seven years.' *(Phil. Trans., lvi.)
veins or anterior cavæ. No. 914 is the anterior part of the In the Museum of the College of Surgeons the prepara body of a large Siren lacertina, prepared to show the heart țion No. 912 shows the anterior part of the body of a Širen and principal vessels injected. The fimbriated structure lacertina. The ventral parietes have been removed, toge- and magnitude of the auricles are well seen when thus ther with the pericardium, to show the heart in situ. It is distended, and they then advance forwards on both sides of of an elongated form, and consists of a large fimbriated the ventricle and bulb, so as almost to encompass those auricle, divided internally into two chambers, and of a flat- parts. The two divisions of the venous sinus may be tened oblong ventricle, giving off a single artery, which, observed below the ventricle, with the termination of the after a half-spiral twist, dilates into an elongated fleshy coronary vein and the attachment of the ventricle to the bulbus arteriosus. The blood from the body passes into a sinus. Behind the ventricle appear two superior cavæ which large membranous sinus formed by the union of the two terminate at the sides of the sinus. The portions of the anterior venæ cavæ with the large posterior cava. The latter lungs which remain are laid open to show their reticulate vessel pours its blood into the sinus by two orifices on either structure, and the relative positions of the pulmonary șide a septum, which extends forwards as far as the open- arteries and veins: white bristles are placed in the former, ings of the anterior cavæ, where it terminates in a 'free and black ones in the lateral vessels. On the left side of semilunar margin ; the sinus is then continued forwards, the preparation, the origin of the pulmonary artery, from and terminates in the chamber analogous to the right au- the posterior branchial arch, is shown. The remainder of ricle. White bristles pass from the posterior cava through the branchial vessels, with the exception of small branches the sinus on either side the septum into the anterior cava. to the head, are collected into one trunk, which unites with A black bristle is passed through the right pulmonary vein the corresponding vessels of the opposite side to form the into the trunk common to the iwo, which traverses but does aorta or systemic artery, The tongue, the interior of the not communicate with the sinus proper to the veins of the air tube, the internal branchial aperture, and the branchiæ body, and terminates in the chanıber analogous to the left of the left side, the eye and nostril
, and structure of the auricle.
integument are also favourably displayed in this preparation, The bulbus arteriosus is laid open, to show the val- ) [PROTEUS and PROTOPTERUS.Í
We now proceed to lay before our readers such other pre- | sides the parts concerned in the circulatory and respiratory parations in this noble collection as illustrate the circulating functions, the stomach, duodenum, liver, pancreas, and system in animals approximating to the perennibranchiate spleen are well shown in this preparation. No. 917 exhibits batrachians, so that the student may compare this part of the heart, pericardium, and trachea of the last-noticed their organization with that of the Siren.
species. Here the ventricle is laid open to show the loose, No.915 shows the anterior part of the body of an AMPHI- fasciculate, muscular structure, which, as in the Testudo UMA (Amph. means, Garden), prepared to show the heart Indica, occupies the whole of its cavity. The bulb of the and great vessels in situ. Professor Owen states that the aorta is laid open to show the two rows of semilunar valves, blood is returned from the body, as in the preceding species, three in each row, and the origins of the branchial arteries. øy two anterior venæ cavæ, and one large posterior cava, The preparation is suspended by the pericardium, behind which form by their union a membranous sinus. The which is the flattened air-tube, in which distinct cartilagiauricles or venous chambers of the heart are proportionately nous rings may be seen. (Catalogue, vol. ii.) smaller and less fimbriated, and are situated more to the Generative System.-No. 2695 exhibits the posterior part left and superior part of the ventricle. The ventricle is of a Siren lacertina, with the ventral parietes of the abdoconnected to the pericardium at its apes, and gives off from minal cavity removed to display the female organs of geneits opposite extremity a single artery, which, after a half- ration. The ovaria are seen as two irregular elongated spiral turn, dilates into a large bulb, which is broader and bodies, situated on each side of the root of the mesentery, shorter than in Siren lacertina, and is grooved externally. and bearing impressions of the convolutions of the intestines. The two pulmonary arteries are given off from the posterior They contain innumerable minute ovisacs of a greyish part of the extremity of the bulb, which then divides into colour, with a few others of a larger size, and of a very dark two branches, each of which again subdivides on the side of colour. The oviducts are external to the ovaria, and are the esophagus. As there are no external gills, so there attached to the sides of the spine, each by a broad duplicaare no lateral branches sent off from the branchial arteries ; ture of peritoneum: they commence anteriorly by a simple, but these, after winding round the arches of the hyoïd bone, elongated, slit-like aperture, without fimbriated margins, terminate in a single trunk on eitber side, and form by and are immediately disposed in about twenty parallel transtheir union the aorta, which is seen, injected, behind the verse folds, which gradually diminish, and finally cease about pharynx. On the left side of this preparation the internal three inches from the cloaca, where the oviducts open branchial aperture is preserved, and on the right side the behind the rectum upon small prominences: bristles are branchial arches of the hyoïd bone are shown. The lungs placed in these outlets. The contracted allantoïd bladder are laid open so as to display their reticulate and longitudi- is seen anterior to the rectum: the posterior extremity of nally plicate structure, and the relative positions of the pul- the kidney extends behind the oviducts, a short way beyond monary arteries and veins.
the cloaca. No. 2696 shows the anterior extremity of the Professor Owen further observes that this preparation is oviducts and liver of a Siren. The oviducts are much igured by Rusconi (Amours des Salamandres Aquatiques, attenuated at their commencement, but soon increase in size, pl
. v., fig. 8) as a portion of the adult Siren lacertina, which and become thicker in their parietes. (Catalogue, vol. ii.) he supposes to have lost the external branchiæ, and to have No preparation of the male organs of the Siren appears acquired the posterior extremities in a manner analogous to to exist in the College Museum; but there are two illustrathe salamanders; and that Rusconi endeavours to invalidate tive of those of Amphiuma and Menopoma, which we proceed the opinion which Hunter, after an extensive and minute to lay before our readers. comparison of their entire structure, had formed of the No. 2397 is the posterior moiety of an Amphiuma (Amspecific difference of the Amphiuma and Siren, as well from phiuma didactylum), with the abdominal cavity laid open, cach other as from the Kattewagve or Menopoma of Harlan. and exposing to view the termination of the intestinal canal, The manuscript alluded to by Rusconi, and which contains supported by its broad and simple mesentery, the terminadetailed accounts of the anatomy of Amphiuma and Me- tion of the right lung, the long allantoïd bladder attached nopomu, as well as of the Siren, is given entire in the de- by a duplicature of the peritoneum to the mesial line of the scription of the plates illustrative of the 2nd vol. of the abdomen, and the testes with their adipose appendages : Museum Catalogue, where (plates xxiii. and xxiv.) the cir- the latter may be observed projecting on each side of the culating and respiratory organs of the 'Chuah Chisstannah, root of the mesentery; and behind them are the testes, or Crawfish-eater, or Kattewagoe' (Menopoma Allegha- elongated, subcylindrical, ash-coloured bodies, tapering at niensis, Harlan (SALAMANDRIDÆ, vol. xx., p. 332], are both extremities: the vasa deferentia descend in the form beautifully displayed; and Professor Owen remarks that of white ligamentous tubes, and finally open into the posthe conclusions as to the distinctions of these amphibia to terior part of the termination of the rectum, which is laid which Hunter arrived, have been subsequently confirmed by open. The renal organs are almost concealed by the parts a similar series of investigations instituted by Cuvier, and above described: they have been injected. No. 2938 above noticed.
exhibits the male organs, kidneys, allantoïd bladder, and No. 916 of the same museum exhibits the lower jaw, large intestine of the Menopome (Menopoma Alleghaniensis). tongue, fauces, with part of the abdominal viscera, and the The testes in this subject are less elongated, and of a more heart in situ of Menopoma Alleghaniensis. The greater compact oval, thus indicating a further stage of advancepart of the pericardium has been removed. The ventricle ment above the class of fishes. The efferent vessels leave is of a flattened triangular form, resembling that of osseous the testis at a longitudinal groove at their posterior and fishes: the auricles are smaller in proportion than in the internal surfaces, at the line of reflection of the supporting Siren, and are situated wholly to the left of the ventricle. processes of peritoneum, and on each side unite to form a The veins of the body terminate in a membranous sinus as deferens, which descends along the edge of a process of situated below tbe auricles. The aorta, after making a spiral peritoneum external to the kidneys, and finally opens into turn to the left side, dilates into a large bulb which gives off ihe termination of the rectum, as in the Amphiume. The fou vessels on each side. The first or posterior pair are kidneys are opake white bodies, which, beginning by small the smallest, and ramify on the æsophagus and lungs; but extremities near the lower end of the testes, slightly enlarge they are not distinctly shown in this preparation. The as they descend to the cloaca. The injected aorta occupies second and third pairs are the largest : they are seen passing their posterior interspace, and there sends off the arteries outwards, and winding round the arches of the hyoïd bone. for the hinder extremities. (Catalogue, vol. ii.) The two branches unite on each side, and, after sending off Siren lacertina grows to the length of three feet: ils small arteries to the head, converge on the posterior part colour is blackish. The feet have four toes, and the tail is of the esophagus, and unite to form the descending aorta. compressed into an obtuse fin. The fourth small pair of arteries pass outwards, and wind over This Siren inhabits the marshy grounds of Carolina, espethe anterior part of the first hyoïdian arch : they send off cially those where rice is cultivated. It lives in the mud, in this course some small arteries to the head, and ultimately from whence it makes excursions, sometimes on land and unite with a cephalic branch given off from the united trunk sometimes in the water. From the swampy places by the of the third and second branchial arteries. The right lung sides of pools and under the overhanging trunks of old is here preserved, and a black bristle is inserted into it from trees where it is found, it was called by the inhabitants the trachea. White bristles are placed in the right branchial the Mud Iguana. Garden was of opinion that it feeds aperture, which is left entire, showing the absence in this on serpents, and that it uttered a cry similar to that of a form, as in Amphiuma, of external gills. On the left side young duck; but Barton contests these statements. Its the branchial arches of the hyoïd bone are preserved. Be food is generally believed to consist of earth-worms, insects,
in the parrot-house in the garden of the Zoological Society in these varieties of form, but maintained a more regular ellipthe Regent's Park. It is kept in a vessel of pond-water tical form; the varieties in question appearing to depend on with a deep bottom of mud, in which it bides itself, and is pressure acting upon the capsule and the coloured fluid twenty inches long, as large as the wrist of a stout child surrounding the nucleus. Yet when the ellipse of the of six months old, and very eel-like in its movements and blood-disc was, as it happened in a few cases to be, longer appearance. About a dozen and a half of earth-worms are and narrower than the average, the form of the nucleus pre. supplied to it as food every other day.
sented a similar modification of size. Siren striata is blackish, with two longitudinal yellow •The following is a table of the averages of many admeastripes on each side; has only three toes on each foot, and surements of these blood-discs, made with the screw microis about nine inches in length.
: 1-850th to 1-870th Long diameter of nucleus
1-1000th Short diameter of ditto
1-2000th Thickness of ditto .
1-3800th (as viewed edgeways covered by the capsule). 'The nucleus was circumscribed by a double line, the outer one more regular than the inner one, which appeared crenated. This appearance was due to the structure of the. nucleus, or the contents of the nucleolar capsule, which was indicated by the outer line. These contents consisted, in every blood-disc examined, of a number of moderately bright spherical nucleoli, sufficiently distinct to be counted, when viewed by a Powell's l-loth inch objective, with the eye-piece, magnifying 700 linear diameters: the ordinary number of nucleoli seen in one plane or focus being from twenty to thirty, the total number was of course much greater. The facility as well as certainty of the demonstration of such a structure in a good microscope of the present day will be readily admitted when it is remembered that the nucleus of the blood-disc of the Siren is three times the size of the entire human blood-disc. These tuberculate nuclei, when removed from the capsule, were colourless ; the component granules or cells have a high refracting power : viewed in situ they present a tinge of colour lighter than that of the
surrounding fluid, and dependent upon the thin layer of that @, head and anterior part seen in profile, showing the branchiæ and foot.
fluid interposed between the nucleus and the capsule. Whilst the article was passing through the press, Pro The external capsule of the blood-disc is smooth, modefessor Owen was so good as to send the following highly in- rately resisting, elastic, as was easily seen by the flattening teresting observations on the blood-globules of the Siren for of the parts of two blood-discs that might come in contact, insertion in this work :
and the recovery of form when they were floated apart. * Among the important generalizations which the nu * As the fluid contents of the blood-disc in part evaporated merous observations of recent microscopical anatomists during the process of desiccation, the capsule fell into folds have enabled the physiologist to establish respecting the in the interspace between the nucleus and the outer conform and size of the blood-discs in different classes of tour, these földs generally taking the direction of straight animals, the most interesting seems to be that which Pro- lines, three to seven in number, radiating from the fessor Wagner has enunciated respecting the relation of nucleus.' (R. Owen, Sept. 25, 1841.) the magnitude of the blood-disc to the persistence of the branchial apparatus in the Batrachian order of reptiles on the occasion of his description of the blood-discs of the Proteus anguinus.
Che absolute size of these particles in that perennibranchiate reptile, in which they may be distinguished by the naked eye, renders them peculiarly adapted for minute investigations into the structure of the nucleus and capsule of the blood-disc: but the value of the relation between their size and the persistency of the external gills must depend upon the correspondence of other perennibranchiate reptiles with the Proteus in this respect. The superior size of the blood-discs of the newts to those of the land-salamanders and tailless Batrachians has been confirmed by
6 Professor van der Hoeven's observations on the blood-discs of the gigantic newt of Japan (Sieboldtia, SALAMANDRIDÆ, vol. xx., pp. 331, 332), of which a fine specimen has been for several years kept alive at Leyden ; and I have been able to add another instance of ihe still greater relative size of the blood-discs in the perennibranchiate reptiles by the examination of those of the largest existing species of Blood-discs of Man aud Siren, drawn by tne camera lucida under a magni. that family, the Siren iacertina, of which a specimen fying power of 700 linear dimeusious.
a, Human blood-discs; a', ditto viewed edgewise ; b. Siren's blond-disc; twenty inches in length is now (October 15th) living at the b', ditto viewed edgewise; c) folds of external capsule, produced by desiccaZoological Gardens. The blood was obtained from one of tion; d, capsule of nucleus ; e, vucleoli. the external gills, and immediately subjected to examination.
SIRENS (Depñves) are described in the 'Odyssey' as two The blood-discs presented the elliptical form which hitherto maidens who sat by the sea and so charmed with their without exception has been found to prevail among the air- music all who sailed by, that they remained on the spot till breathing oviparous vertebrated animals: the ellipse was not they died. Ulysses, by the direction of Circe, had himself quite regular in all the blood-discs; several were sub-ovate, tied to the mast, and stopped the ears of his companions a few slightly reniform and thicker at the more convex with wax, by which means he was able to hear their music, side: all were as compressed, or disc-shaped, as in other and escape from its inttuence. (Od., xii. 39, &c., 169.) The Batrachians, with the nucleus slightly projecting from each
. I was indebted to Mr. Stokes for the use of the one attached to his ad of the flattened surfaces.
mirable dzimtoscope by Powell.