16 NEW-YORK FAUNA — CRUSTACEA. 



Front entire : third joint of the anterior pair serrate on the inner edge, and four-toothed at the 

 tip. Hands large, granulate beneath. Carpus with an obtuse spine. Tarsi short and spi- 

 nous beneath. 



Color, variable, but most usually brownish, mottled with ash. Eyes reddish brown. 



Length, - 3. Transverse diameter, - 2. 



This little species is usually found upon seaweed, or the larger marine animals in the 

 ocean. It has been noticed on seaweed off the harbor of New-York. But a single species 

 is yet known. 



GENUS PLAGUSIA. Latreille. 



General form of the preceding, but the internal antennae are short, vertical, and moving in 

 deep cavities which are open above, and formed in the substance of the shield. Mouth 

 nearly closed in front. 



Plagusia sayi. 



Plagusia deprcssus. Say, Jour. Acad. Nat. Sc. Vol. 1, p. 100. 



Description. Shield with numerous distant punctures, having the appearance of being 

 covered with scales, each of which is bounded before by a line of impressed points furnish- 

 ing hairs. Sides of the shield with three serrate teeth ; the posterior canthus of the eye 

 elevated into a tooth, with a small tubercle within its base. Carpus with a depressed spine 

 within, which is emarginate at tip. Hands granulate above, with small tubercles and two 

 impressed lines. Tarsi with a double line of movable spines beneath ; tip of the preceding 

 joint about five-spined beneath. 



Color, variegated ; tibia darker, spotted ; beneath white, immaculate. 



Mr. Say received this species from the Gulf stream, and considered it as synonimous with 

 the P. depressa from the Indian ocean and coast of China. From this it is distinguished by 

 the hairy tubercles on its shield. I agree with M. Milne-Edwards in considering it more 

 allied to P. squamosa from the Red sea and Indian ocean. This latter, however, is charac- 

 terized by its shield bristling with elevated tubercles, each of which is furnished with a series 

 of stiff hairs directed forward, and resembling scales. It may provisionally, until a direct 

 comparison is made, be considered as a new species, taking of course the name of its learned 

 and indefatigable discoverer 



