262 REPORT OF NEW JERSEY STATE MUSEUM. 



Last four pairs of legs ambulatory. All legs with spines and 

 hairs along free edges. Opercular valves in two parts, small 

 tenninal part representing outer branch of uropoda. Inner 

 branch represented on under side, attached to basal portion on 

 exterior side. 



Color variable, usually dark grayish, much like wet sand in 

 which animal lives. Top of thorax usually dark leaden-gray, 

 sometimes with central spot of bright pea-green, probably from 

 contents of digestive tract showing through. This dark color 

 continued in an arrow-shaped or halberd-shaped spot, occupying 

 most of upper surface of head. All sides of head and body mot- 

 tled light yellowish-gray, darker again on edge. Body below, 

 including legs, uniformly pale. Colors usually fade uniform 

 straw color in alcohol, with fine blackish dots, doubtless less con- 

 spicuous in life. 



Length 12 to 15 mm. (O. Harger and H. Richardson.) 



Remarks. — The range of this species is from New Brunswick 

 to Florida. It occurs along the shores of sandy beaches below 

 high tide, or burrows just under the surface. It is a good 

 swimmer. 



Super-Family CYMOTHOIDEA. 



First pair of legs not cheliform. Uropoda lateral, not terminal, 

 and forming, with last abdominal segment, a caudal fin or fan 

 as in shrimps and lobsters. Pleopoda mostly natatory. 



Isopods of various structure, and mostly parasitic, or semi- 

 parasitic, and for this cause legs often more or less prehensile. 

 Families about twelve. 



Key to the families. 



a. Uropoda entirely lateral. 



b. Abdomen of two segments. 



c. Both branches of uropoda present. sph^romid^- 



cc. Outer branch of uropoda entirely absent. anciniDjE. 



bh. Abdomen usually of six segments. 



d. Uropoda with one of rami almost obsolete or rudimentary, not 

 lamelliform. limnoriid.*. 



