1818.] OF THE UNITED STATES. 425 



interval; three anterior pairs of feet monodactyle; eyes 



inconspicuous. 



Inliabits coast of the United States. 



Cabinet of the Academy. 



Body broadest at the third segment; three abdominal 

 -segments Uctrrowest; head quadrate, immersed, depres- 

 sed, a profound fissure on the lat^eral edge; antenna as long 

 as the head, equal; taily first segment shori, second some- 

 what trilobated, middle lobe interrupting the preceding 

 segment above, ultimate segment half as long as the bo- 

 dy, attenuated to an acute point, convex and subcarinate, 

 above, margin near the tip suddenly depressed; feet gra* 

 dually longer to the posterior ones which are longest, 

 three anterior pairs robust, monodactyle, remaining ones 

 simple, unarmed, furnished with rigid hair or seta&; naiU 

 f)f the hind pairs rectilinear, tipped with setae. 



Length nearly three tenths of an inch; one specimen 

 was upwards of two fifths. 



Found in the small pools of sea- water, left by the re- 

 fluent tide. Colour when recent, whitish, varied with 

 brown dots, which are sometimes nearly united into bands; 

 eyes milk-white; head vrith a transverse black band, which 

 is angulated behind, a large milk white spot on the back 

 and a smaller triangular one before the tail, both some- 

 times obsolete; swims on its back, and conceals itself in 

 the sand; found as far south as Florida. 



2. I. #r?7oifl*. Body oval, somewhat oblong; seg^ 

 ments with the lateral processes convex; intermediate an* 

 tenna short; feet armed with strong curved nails. 



Inhabits Egg-harbour, 



