260 



MARINE INVERTEBRATES 



Prawns are known as crevettes in France and as Garnelen in 

 Germany, where they are largely used as food. In the United 

 States the shrimp-fishery is an industry of the South. On the 

 California coast the fisheries are very extensive and are monopo- 

 lized by the Chinese. 



GENUS Penceus 



P. setiferus. This species is about six inches in length when full- 

 grown. A ridge or crest extends along the center of the carapace, and 

 terminates in a long, pointed, toothed rostrum, the teeth being fringed 

 with hair on the inner side. The antennae are a foot or more in length ; 

 there are chelae on the first three pairs of thoracic feet ; the swimming- 

 feet and lateral margins of the segments of the abdomen are fringed 

 with hair ; and the caudal appendages are longer than the telson. It 

 ranges from Virginia southward, and is very abundant on the shores of 

 the Southern States, where it is gathered for the markets. The large 

 ones are known as prawns and the small ones as shrimps. 



JP. brasiliensis. This species is associated with P. setiferus, and, al- 

 though not so abundant, forms a part of the shrimp-supply in the fisher- 

 ies. It differs from the former in having a groove on each side of the 

 ridge which runs through the center and whole length of the carapace. 

 The first three pairs of feet are chelated. This shrimp is found as far 

 north as Long Island, and often in brackish water, or even where the 

 water is quite fresh. 



GENUS Palcemonetes 



vulgaris; male. 



ish water, and also in pools and ditches 

 Massachusetts Bay to Florida. Commonly known as prawns. 



.P. vulgaris (Palce- 

 mon vulgaris). Aver- 

 age size one half of an 

 inch in length ; body 

 translucent, almost color- 

 less, irregularly spotted ; 

 rostrum as long as cara- 

 pace and toothed on the 

 upper edge. It is found 

 among eel-grass in brack- 

 on muddy shores from 



GENUS Crangon 



C. vulgaris, the common sand-shrimp. It ranges from Labrador to 

 North Carolina on the Atlantic coast and from Alaska to southern Cali- 

 fornia on the Pacific coast. It is found in abundance on sandy shores at 

 low-water mark, and in shallow water below tide-mark ; also among 

 rocks and seaweeds. When left by the tide it buries itself in the sand. 

 Its color varies with its location, rendering it inconspicuous. Upon the 



