ISO I^otes on Nortli American Crustacea, 



genus this diiFers in the divergence of the rostral horns. Pisa 

 styx and P. aculeata will be here included. 



IflilBiia bicornuta. 



Pisa bicornuta Latr. 



Perkera bicorna M. Edw. ; Hist. Nat. des Crust, i. 337. 



Pisa bicorna Gibbes. 



Pericera bicornis Sauss, Crust, nouv. de la Mexique, etc. p. 12, pi. i. f. 3. 



AYe do not know why M. Edwards changed Latreille's name 

 hicornuta to hicorna. The latter is probably a misprint for 

 'bicornis^ but has been in common use since the publication of 

 Milne Edwards' work. 



This is a common West Indian species, and has been received 

 in abundance from the coral-reefs of Florida, from all who 

 have made collections there for the Smithsonian Institution. 



Milnia platysoitia, nov. sp. 



Allied to Pisa aculeata Bell, but presents the following dif- 

 ferences. Carapax depressed, but of less breadth, and sparsely 

 granulated. There are only two laminiform processes on the 

 antero-lateral margin, — one on the hepatic region, and the 

 other on the branchial, which latter does not project in an im- 

 bricated mannner. Between these processes and below their 

 level there is a spine. There are only two spines on the bran- 

 chial region, and these are scarcely more than sharp tubercles. 

 There is a row of bead-like tubercles on the superior edge of 

 the posterior margin. The rostrum is more flattened than in 

 M. aculeata^ the orbits more tubular, and the prseorbital teeth 

 sharper. The basal joint of the external antennae is very broad, 

 and is armed with two teeth or spines on the surface near the 

 postero-exterior angle. The feet are short and depressed, 

 and armed with spines as in aculeata / penult joint with a 

 broad, rounded, lamelliform process for the articulation of the 



