170 New York State Museum 



(F. thraciaeformis), shaped like the blade of an axe, is 

 also found along the New England coast, Long Island 

 sound and southward. The shell is two and one-half inches 

 long with a height of one and one-half inches and 

 has an oblique wavelike rib. The epidermis is dark olive- 

 green. Other species occur on our Northern coasts, and 

 on the Calif ornian and Alaskan shores. 



Crustaceans are well represented on muddy bottoms. 

 Among them are the Common Prawn, the Mantis Shrimp, 

 the Feather- footed Shrimp, the Horseshoe or King Crab, 

 the Blue or Edible Crab, Spider Crabs, Hermit Crabs, the 

 Fiddler Crabs and the Mud Crabs. The Blue or Edible 

 Crab (CaUinectes sapidus) is the common edible crab of 

 the Atlantic coast, ranging from Cape Cod to the Gulf 

 of Mexico. In the south it is known as the Sea Crab. 

 It inhabits muddy shores and is common in shallow bays 

 and estuaries where the bottoms are muddy and covered 

 with eel-grass and the water may be brackish. They re- 

 tire to deeper waters in the winter time. This crab sheds 

 its shell once during the summer, remaining soft for a 

 few days, and it is then the "soft-shelled" crab of our 

 markets. The last pair of legs of this crab are paddle- 

 shaped, modified for swimming, and it may always be 

 recognized by the sharp spire that projects outward on 

 each side of the body. It may attain a width of six 

 inches. Very closely related forms occur on the African 

 coast, along our Pacific coast and in the West Indies. 

 The Common Prawn (Palaemonetes vulgaris) is espe- 

 cially abundant on muddy bottoms in shallow brackish 

 water. It has a range from Massachusetts to Florida, but 

 is rare north of Cape Cod. It grows one and one-half 

 inches long and is distinguished from the Common 

 Shrimp by the sharp-pointed, saw-edged spine that pro- 



