. Animal physiology. Physiology, Comparative; Physiology, Comparative. Fig. -Early Form of a Crab. to approach the complete metamorphoses of insects, and which end in the production of the complete form. An early form of the common crab, at a time when it is of the minute size indicated on the scroll, is shown in Fig. 49. 109. Now the immature Crustacea of different tribes bear much more resemblance to each other, than do the forms into which they are ultimately to be developed; and the differences they afterwards present are chiefly due to a variety in the amount of growth, which the dif
. Animal physiology. Physiology, Comparative; Physiology, Comparative. Fig. -Early Form of a Crab. to approach the complete metamorphoses of insects, and which end in the production of the complete form. An early form of the common crab, at a time when it is of the minute size indicated on the scroll, is shown in Fig. 49. 109. Now the immature Crustacea of different tribes bear much more resemblance to each other, than do the forms into which they are ultimately to be developed; and the differences they afterwards present are chiefly due to a variety in the amount of growth, which the different parts undergo. Thus in the crab, the thorax is developed at the expense of the abdomen or tail; in the lobster and cray-fish, the hinder part of the body is developed at the ex- pense of the front. This variation in the development of the same parts is most remark- ably shown in regard to the members connected with the segments forming the head and the front of the thorax. In the Limulusor king-crab, of which the under surface is shown in Fig. 50, these members, p, are fully de- veloped around the mouth b ; and they are so formed, as to serve either as legs or claws; whilst the joints nearest the mouth act the part of jaws. Beneath the hinder portion of the body are appendages, a b, w7hich support the gills. But, as may be readily supposed, these feet-jaws do not perform the functions of movement or of. Fig. 50.— Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Carpenter, William Benjamin, 1813-1885. London : Wm. S. Orr and Co.
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