134 ZOOLOGl' 



dead, animal or plant. On account of the need of calcareous 

 matters in the food, crayfishes are especially fond of the 

 stoneworts (Chara) and various succulent roots, like the carrot. 

 It is said that craj^fishes sometimes make excursions inland in 

 search of plant food. They likewise devour shells of snails, 

 their own cast-otf skins, and occasionally one another, shell 

 and all. 



The crayfish belongs to the class of Crustacea, since it 

 breathes by means of gills, possesses two pairs of antennce, 

 a pair of mandililes bearing palps, and a pair of apj^endages 

 on all body segments excepting the last. The Crustacea are 

 di^'^ded into two subclasses, — Entomos'traca, of which 

 Daphnia is an example, and ]Malacos'traca, to which the cray- 

 fish l)elongs. All the Malacostraca ^ have nineteen pairs of 

 appendages. 



The lobster (Homa'rus) is, as we have already seen, the 

 nearest li\'ing salt-water relative of the cra^disli. There are 

 only two species of the genus Homarus. One, Homarus 

 americautis, occurs on our Atlantic coast; the other, H. vulgaris, 

 is the lobster of Europe. On our Pacific coast there is the 

 " spiny blaster," l3ut this is not closely related to the Eastern 

 lobster (Fig. 131). Tlie national government has transplanted 

 the Atlantic lobster to several localities on the Pacific coast, 

 but it is not yet known whether it will thri^-e there. The 

 American lobster ranges from Labrador to Delaware Bay, 

 and from near shore to a depth of 100 fathoms. It attains 

 its greatest size on the rocky shores in the cooler waters from 

 Maine to Lalirador. It migrates but httle along the coast; 

 in the fall, however, it moves out into deep water, and in the 



iFrom maktkos, soft, ostrakon, shell; since the shell is less hard than that 

 of moUusks. 



