418 PROCEEDINGS OF THE ACADEMY OF [1819. 



pus of the second pair with the first two joints equal, and each as 

 long as the third and fourth together, which, in turn, are subequal, 

 and each slightly shorter than the fifth joint. This species, in a 

 systematic arrangement of the North American forms, would stand 

 between A. heterochelis and A. transversodactylus, but more nearly 

 to the former. The differences from that species are not easy to 

 describe, but are well marked in the specimens. 



1 have dedicated this species to my friend and former instructor, 

 Dr. Aipheus S. Packard, Jr., not only as a token of esteem, but 

 also from a recognition of the appropriateness of the name. Three 

 males from Key West. Length, 22 mm. 



Aipheus candei Guerin in de Sagra's Historia de Cuba Crustaces 

 (p. L. pi. ii. f. 9). Aipheus transversoda.ctylus Kingsle}'. Two spe- 

 cimens were taken at Key West. 



Bes des these species of Aipheus there is a single specimen ap- 

 proaching A. candei most nearly in form, but differing from that 

 species in form of front, and in having a large swollen pyriform 

 hand without grooves, etc., which I hesitate to describe as new. 



o Genus Alope White. 1 Rostrum short, toothed above, and 

 placed in a groove formed by two spines which arise at the ante- 

 rior portion of the carapax, and extend nearly as far as the ros- 

 trum. Eyes but little salient, antennulre biflagellate ; external 

 maxilliped very long ; hands of first pair of pereiopoda equal; 

 carpus of second pair annulate. Type Alope palpalis White. 



Genus Arete Stimpson.' 2 Rostrum short, rounded above; ej'es 

 free, antennuhe biflagellate; antennal scales larger. External 

 maxillipeds slender, moderate; hands of first pair of pereiopoda 

 large, equal, inversely depressed ; dactyli external; second pair 

 short; carpus 4-articulate. Type Arete dorsalis Stm. 



o Genus Athanas Leach. Rostrum short ; antennulse triflagel- 

 late ; eyes but little salient ; external maxillipeds short, slender. 

 Frst pair of pereiopoda long, stout, unequal; second filiform ; car- 

 pus 5 articulate. 



Genus Hippolyte Leach. 3 Rostrum moderate, more or less 



1 Annals and Magazine of Natural History, second series, vol. i. p. 225, 

 1848. 



2 Proc. Acad. Nat. Sci. Philadelphia, 1860, p. 32. 



3 Bellidia Gosse. Annals and Magazine of Natural History, 4th series, 

 vol. xx. p. 313 (1877). I have not seen Costa's description of Peridemenes 

 (Annal. del Accad. degli Aspiraz. Natur di Napoli II. p. 285, 1844). Erichson 



