134: Notes on North American Crustacea^ 



insertion of the antennulse, and one at the antero-inferior corner of 

 the carapax. Rostral crest extending only as far back as the first or 

 posterior tooth, which is situated at about the anterior third of the 

 length of the carapax, and far distant from the second tooth, which 

 is placed over the base of the eye-peduncle. Beyond and including 

 this second tooth there are seven teeth on the superior margin of 

 the rostrum, and perhaps more, as the tip is broken in our speci- 

 men. There are no teeth on the inferior margin. The rostrum, 

 in its broken condition, reaches to about the middle of the penult 

 joint of the peduncle of the antennulse. Eyes very large. Anten- 

 nulse short, as in P. setiferus / the lamelliform appendage at its base 

 is small, long-ciliated, and pointed, not dilated, at its extremity ; fla- 

 gellum veiy short. Antennas only as long as the body ; the antenual 

 scales are a little shorter than the peduncle of the antennvil^e. Feet 

 unarmed at base ; hands of the third pair very slender. Abdomen 

 carinated from the middle of the second joint backward to the sixth 

 joint, the carina becoming sharper and prominent towards its poste- 

 rior extremity ; seventh or caiidal joint sublanceolate, very slightly 

 furrowed above, without carinse, and terminating in an acute spine, 

 with a smaller spine on either side at its base. Caudal lamellae pubes- 

 cent ; the inner one longitudinally bicarinated in the middle, not sul- 

 cated as in P. hrasiliensis and P. setiferus. 



Of this species I have seen but one specimen, a female, two 

 inches in lengtli, excludinsj the antennae. 



It was presented to the Institution by A. H. Eiise, Esq., who 

 collected it at St. Thomas. 



Penaeus styliro!$tris, nov. sp. 



Somewhat allied to P. setiferus, but with the following well-marked 

 distinctive characters. The carapax behind the rostrum is obtusely 

 carinated nearly to the posterior extremity; the carina being some- 

 times furrowed along the middle for a short distance at the point 

 where the cervical sulcus would cross if continued, at which point 

 there are two small pits indicating the attachment of the posterior 

 supports of the stomach. Rostrum long, over-reaching the antennal 

 scales, four-toothed below, and, including carina of the carapax, eight- 



