. Natural history. Zoology. WOOD-LICE AND WHALE-LICE. 535 always seven pairs of legs, and the abdomen and its appendages are also well developed in some families, tlio hinder segments bearing long legs adapted for leaping. This description applies best to the Oammaridce, one or two of which, that live in fresh water, grow to the length of half an inch. The greater part of the AmpMpoda, however, are marine, and differ considerably in size, shape, and habits. Some swim freely in the water, and others burrow into woodwork. Many are in the habit of attaching them- selves to various marine animals;
. Natural history. Zoology. WOOD-LICE AND WHALE-LICE. 535 always seven pairs of legs, and the abdomen and its appendages are also well developed in some families, tlio hinder segments bearing long legs adapted for leaping. This description applies best to the Oammaridce, one or two of which, that live in fresh water, grow to the length of half an inch. The greater part of the AmpMpoda, however, are marine, and differ considerably in size, shape, and habits. Some swim freely in the water, and others burrow into woodwork. Many are in the habit of attaching them- selves to various marine animals; and one family, Lmnodi- podidw, in which the abdomen is rudimentary, is truly parasitic. One curious genus, Cyamus (Lamarck), which is parasitic on whales, has strong hooked appendages at both ends of the body; and the species are known as Whale- Lice. We have figured 0. ovalis (Roussel).. Fig. 9.— \Vhale-Louse (Cyamus ovalis). Nat, gize. Order II.—Thoracostraca. The present order agrees with the last in the number of segments, but is distinguished from it by having more or fewer of the thoracic segments united with the head by a common shell, or carapace, and there are usually two compound stalked eyes. We find no true parasites in this group, though some of them seek the society of other animals for the sake of food and shelter, as in the case of the small crab which takes up its residence in the shell of the Pinna. Sub-Order I.—Cumacea. Includes small marine species, with sessile eyes, and a long, slender abdomen. Sub-Order II.—Stomatopoda. This order is now restricted to the single (amilj S;£HilUdce, which are marine Crustacea resembling large prawns, three inches or more in length, with the cephalothorax slender, a large tail-fin, and the second pair of foot-jaws developed into an enor- mous claw, which has led to one of the com- mon species being called Squilla mantis (Eondel), on account of the shape and attitude of its legs very closely resembling the predaceo
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