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fragments of minute mussel and crab shells; and there, inserted in the spongy, conical, yellowish-colored liver, and somewhat resembling in form a Florence flask, was the inkbag distended, with its deep dark sepia-the identical pigment sold under that name in our color-shops, and so extensively used in landscape drawing by the limner. I then dissected and laid open the circular or ring-like brain that surrounds the creature's parrot-like beak, as if its thinking part had no other vocation than simply to take care of the mouth and its pertinents almost the sole employment, however, of not a few brains of a considerable higher order. I next laid open the huge eyes. They were curious organs, more simply in their structure than those of the true fishes, but admirably adapted, I doubt not, for the purposes of seeing. A camera obscura may be described as consisting of two parts. a lens in front, and a darkened chamber behind; but in the eyes of fishes, as in the brute and human eye, we find a third part added: there is a lens in the middle, a darkened chamber behind, and a lighted chamber, or rather vestibule, in front. Now, this lighted vestibule-the cornea-is wanting in the eye of the cuttlefish. The lens is placed in front, and the darkened chamber behind. The construction of the organ is that of a common camera obscura. I found something worthy of remark, too, on the peculiar style in which the chamber is darkened. In the higher animals it may be described as a chamber hung with black velvet the black pigment which covers it is of the deepest black; but in the cuttle-fish it is a chamber hung with velvet, not of a black, but of a dark purple hue. There is something interesting in marking this first departure from an invariable condition of eyes of the more perfect structure, and in then tracing the peculiarity downwards through almost every shade of color, to the emeraldlike eye-specks of the pecten, and the still more rudimentary red eye-specks of the star-fish. After examining the eyes, I next laid open, in all its length, from the neck to

the point of the sack, the dorsal bone of the creature. its internal shell, I should rather say, for bone it has none. The form of the shell in this species is that of a feather, equally developed in the web on both sides. It gives rigidity to the body, and furnishes the muscles with a fulcrum; and we find it composed, like all other shells, of a mixture of animal matter and carbonate of lime.

the lesson taught me in a single walk.

Such was

H. Miller.

THE NEMERTES.

If we would observe the extreme limit to which degradation of type may attain in the articulata, we must descend to the class of worms, properly so called. Here great size is often associated with extreme simplicity of organisation; a circumstance which is nowhere else exhibited in so high a degree, not excepting even the radiata. The Nemertes* presents a very remarkable instance of this. Figure to yourself an animal from thirty to forty feet in length, and only five or six lines in width, flat as a riband, of a brown or violet color, and smooth and shining as varnished leather. This gigantic worm lurks under stones and in the hollows of rocks, where it may be met with rolled into a ball and coiled into a thousand seemingly inextricable knots, which it is incessantly loosening and tightening by the contraction of its muscles. This animal is nourished by sucking the anomia, a kind of small oyster, which attaches itself to various substances under water. When it has exhausted the food around it, or when it wishes to change its position, it extends its long, dark-colored, riband-like body, which is terminated by a head, bearing some resemblance to that of a serpent, although it has neither the large mouth nor the formidable teeth of the latter animal. In observing it in motion, the eye is unable to detect any contraction, or

*Nemertes, i. e. N. Borlasii.

any apparent cause by which it is enabled to move, and it is only by the aid of the microscope that we learn that the nemertes glides through the water by means of excessively fine vibratile cilia, which are protruded from every part of the surface of the body. It pauses, gently moves from side to side, as if endeavouring to investigate the ground, until it at length succeeds in finding a stone to suit its purpose, lying perhaps some fifteen or twenty feet from its former retreat. It then begins to unwind its coils, in order to arrange itself in its new domicile, and in proportion as one knot is loosened another forms at the opposite extremity. We may remark that the contractility of the tissues of this animal is so great, that a nemertes thirty feet long scarcely exhibits one-tenth of this length after being immersed in alcohol, when it will be found to measure no more than two and a half or three feet.

All the great apparatus of life is represented in the organisation of the nemertes, although it is here reduced to its simplest expression. The nervous system does not form that œsophageal ring, which has long been regarded as characteristic of the type. Here it is composed simply of two lateral ganglia, whence proceed two cords, which extend to the extremity of the body, and give off merely very small threads. Two large vessels, placed on either side, accompany these nervous trunks, a third winds along the median line; all three are simple, without ramifications of any kind. The mouth consists of a circular orifice, which is scarcely visible, and opens into a long tube, separated by a constriction from the intestine, which terminates in a cul-de-sac. Thus the same opening serves for the introduction of the food, and for the rejection of the undigested residue. As if to compensate for the low degree of development in these organs, the ovaries, which are placed on either side of the body, are of very considerable dimensions. This very circumstance, however, is in itself an indication of the inferiority of the animal. These de

graded species are besides exposed to a thousand chances of destruction in the earlier period of their existence; at a more advanced age, they usually serve for the food of higher forms of animals. Hence nature has provided largely for their multiplication. Many of them literally become transformed into ovigerous sacs. Thus, for instance, in the case of a nemertes, measuring from eight to ten feet in length, we cannot estimate the number of ova at less than four or five hundred thousand. Quatrefages.

THE WORM.

AN examination of the diverse modes in which locomotion is performed among animals, and the various organs and modifications of organs that subserve this important purpose, should form an interesting chapter in natural history. You have two feet, your dog has four; in the bird two of these are converted into wings, with which it rises into the air; in the fish all of them are become fins, with which it strikes the water. But it is in the invertebrate classes that we discover the strongest variations. The poulpe "flops" awkwardly but vigorously along by the alternate contractions and expansions of the web that unites its arms ; the snail glides evenly over the herbage by means of its muscular disk; the scallop leaps about by puffs of water driven from its appressed lips; the lobster shoots several yards in a second by the blow of its tail upon the water; the gossamer spider floats among the clouds upon a balloon that it has spun from its own body; the centipede winds slowly along upon a hundred pairs of feet; the beetle darts like an arrow upon three; and the butterfly sails on the atmosphere with those painted fans which are properly "aerial gills." How elegantly does the planaria swim by

the undulation of its thin body, and the medusa by the pumping forth of the water held within its umbrella! How wondrously does the echinus glide along the side of the tank on its hundreds of sucking-disks! How beautiful, and at the same time how effective, are the ciliary wheels of the brachionus.

I am now going to show you some other examples of travelling machinery in a humble and despised, but far from uninteresting class of animals-the worms. Here is an earth-worm upon the garden border. With what rapidity it winds along, and now it pokes its sharp nose into the ground, and now it has disappeared! If your eye could follow it, you would see that it makes its way through the compact earth not less easily nor less rapidly than it wound along the surface. If you take it into your hand, you perceive no feet, wings, fins, or limbs of any kind; only this long cylinder of soft flesh, divided into numerous successive rings, and tapering to each extremity. The very snout which you saw enter so easily into the substance of the soil, is no hard bony point, but formed of the same soft yielding flesh as the other parts. And yet with no other implement does the lithe worm penetrate whithersoever it will through the ground. How does it effect

this?

The fineness of the point to which the muzzle can be drawn is the first essential. This can be so attenuated that the grains of adherent soil can readily be separated by it, and then its action is that of the wedge. The body being drawn into the crevice thus made, the particles are separated still farther. Now another provision comes in ; the whole surface of the skin secretes and throws off a quantity of tenacious mucus or slime, as you will immediately perceive if you handle the worm; this has the double effect of causing the pressed particles of soil to adhere together, and then to form a cylindrical wall, of which they are the bricks, and the slime the mortar, and also of greasing, as it were,

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