File:Image from page 124 of "Introduction to zoology; a guide to the study of animals, for the use of secondary schools;" (1900) (14598285110).jpg

Identifier: introductiontozo00dave Title: Introduction to zoology; a guide to the study of animals, for the use of secondary schools; Year: 1900 (1900s) Authors: Davenport, Charles Benedict, 1866-1944 Davenport, Gertrude Anna Crotty, 1866- Subjects: Zoology Publisher: New York, Macmillan company London, Macmillian and co., ltd. Contributing Library: MBLWHOI Library Digitizing Sponsor: MBLWHOI Library

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Text Appearing Before Image: c., have been found inthe stomachs of lobsters and crayfish, which likewise wouldprobably have been dissolved and used in hardening theshell. Shrimps and prawnsl belong to a thin-skinned, long-tailedfamily of Crustacea.2 They are extremely common in bays 1 These are common names of small Crustacea applied chiefly to thedecapod family Carididse,* although also applied to certain Schizopods.The term shrimp is applied to the smaller species, and prawns to thelarger. 2 Fig. 90. * (capis, a small marine crustacean. THE CRAYFISH AND ITS ALLIES 105 along our coast, and even penetrate into rivers. Two rivershrimps l are found in the United States east of the Missis-sippi River. These Crustacea are able to maintain theirenormous numbers only by virtue of their great repro-ductive capacity, necessitated by the circumstance thatthey furnish almost the entire food supply for many kindsof fishes and other foes. Even in the principal shrimpinggrounds of the United States- -such as San Francisco and

Text Appearing After Image: FIG. 97. — Gebla affinis, right side. Two-thirds natural size. Photo, by W. H. C. P. New Orleans — there is said to be no diminution in thenumbers of shrimps. The Thalassinidae2 include certain crayfish-like specieswhich live on our coast, burrowing in mud-flats, wherethey live concealed during the day. On account of theirbeing of only medium size and difficult to obtain, they arecommonly little known. Our Eastern species are Grebiaaffinis (Fig. 97) and Callianassa stimpsoui. The hermit crabs (Pagurida33) occupy a position inter-mediate between the long and short tailed Decapods in 1 Palwmon Ohionis and Paleomonetes exilipes. 2 0a\d(Tcrivos, color of the sea. 3 irdyovpos, a kind of crab. 106 ZOOLOGY respect to the length of their abdomen. The abdomen issoft, and the animal protects it by inserting it within thecoiled shell of some gastropod. Moreover, the abdomen isasymmetrical, being coiled to one side to correspond withthe shape of the borrowed house (Fig. 99). The abdominalfeet

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