Title: Comparative zoology, structural and systematic : for use in schools and colleges
Identifier: comparativezool00orto (find matches)
Year: 1883 (1880s)
Authors: Orton, James, 1830-1877; Birge, E. A. (Edward Asahel), 1851-1950
Subjects: Zoology; Anatomy, Comparative; Physiology, Comparative
Publisher: New York : Harper & Bros.
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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AKTHROPODA. 283 pressed into a very small space, yet have the following members: the eye-stalks; the short and the long anten- nae; the mandibles, or jaws, between which the mouth opens; the two pairs of maxillae; and a pair of modified limbs, called " foot-jaws." The thorax carries two more pairs of foot-jawrs and five pairs of legs. The foremost legs, "the great claws," are extraordinarily de- veloped, and terminat- ed by strong pincers (chelce). Of the four slender pairs succeed- ing, two are furnished with claws, and two are pointed. The last pair of swimmerets, to- gether with the telson, form the caudal fin— the main instrument of locomotion; the others (called "false feet") are used by the female for carrying her eggs. The eyes are raised on stalks so as to be mov- able (since the head is fixed to the thorax), and are compound, made up of about two thousand five hundred square facets. At the base of each small antenna is a minute sac, whose mouth is guarded by hairs: this is the organ of hearing. The gills, twenty on a side, are situated at the bases of the legs and enclosed in two chambers, into which water is freely admitted, in fact, drawrn, by means of a curious attachment to one of the
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Fig. 250.— Under-side of the Cray-fish, or Fresh- water Lobster (Astacus fluviatilis): a, first pair of antennae; b, second pair 4 c, eyes ; <7, open- ing of kidney; e, foot-jaws ; /, g, first and fifth pair of thoracic legs; h, abdominal feet; i, anus; Jc, caudal fin.

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