26 NEW- YORK FAUNA CRUSTACEA. 



tending nearly to the posterior margin of the thorax. Eyes sessile, and resting upon the con- 

 cave surface of the peduncle of the interior antennae. Outer antennae nearly equalling the 

 total length, and furnished with an oblong tapering plate, truncate at the tip, nearly as long 

 as the internal antennae, with a raised external border, and ciliate on the internal margin with 

 long hairs. Anterior feet with a slender curved claw, opposable to a sharp prominent spine. 

 Second and third pair of feet exceedingly slender ; the remainder more robust, and all with 

 simple acute tips. Middle caudal plate simple, conic, concave beneath ; outer plates oblong- 

 oval, margined with hairs. 



Color, very pale greenish, frequently translucent ; the basal plates of the external antennae, 

 and the caudal plates, punctate with brown. 



Length, T5-1-75. 



This is a lively little animal, and known under the popular name of Bait Shrimp, being used 

 exclusively for bait. M. Edwards observes that this differs very little from the C. vulgaris, or 

 Common Shrimp of Europe, but admits that it may probably be a new species. In his edition 

 of Lamarck's Animaux sans vertebres, published subsequently to his work on the Crustacea, 

 he passes it over in silence. Dr. Gould considers the two species as identical ; there appears, 

 however, to be a notable difference in the shape of the basillary plates of the external antennae. 



In many parts of Europe, the Shrimp is eaten in great quantities. Our species has a wide 

 geographical range, being found from Florida to the Arctic ocean. 



{EXTRALIMITAL.) 



C. boreas. (Phipps, Voyage, p. 194. Muller, ZooLDan. Vol. 4, pi. 132, fig. 1.) Shell rough, armed 

 along the medial line with a trifid crest. The plate of the external antennae short and very wide. 

 Second and third pair of feet filiform ; feet of the two last pair very large. Medial plate of the tail 

 with seven spines. Color, variegated with reddish. Length, 5-0 — 7' 0. Stomachs of Cod-fish 

 Coast of Massachusetts. 



Genus Alpheus, Fabricius. Antennae arranged in two series, the internal above the external. First 

 and second pair of feet didactyle. Hands of the first pair large and unequal ; the three last 

 pair monodactyle. Shield advanced above the eyes. Inhabiting the seas of warm climates. 



A. helerochelis. (Say, loc. cit Vol. 1, p. 243.) Rostrum simple, spiniform, acute, carinate in the middle. 

 Shield smooth, without spines. Larger hand di formed, compressed, abruptly constricted near the 

 fingers on each edge. Color, green, with small brownish spots ; hand beneath white. Length, 

 1-5. Florida, South-Carolina. 



A. minus. (Id. loc. cit.) Rostrum and shield over the eye, forming three spines in front. Larger 

 hand not compressed, inflated. External jaw-feet obtuse at point, and crowned with spines. Color: 

 Large hand white, the tip red, banded near the bases of the fingers with white in the female ; white 

 tipped with green in the male. Length, 0*8. South-Carolina and Florida. 



