1894.] NATURAL SCIENCES OF PHILADELPHIA. 407 



Atyoida the hands are formed like those of Caridina: the dactylus 

 (movable finger) is inserted on the upper margin of the propodus, 

 being shorter than the latter and forming a chela, as usual in the 

 Deeapoda, consisting of a palmar portion and two fingers. In Atya, 

 on the contrary, the dactylus articulates with the propodus on the 

 posterior end of the latter, both joints being exactly alike and form- 

 ing a hand of a very peculiar shape among the Deeapoda, the 

 palmar portion being wholly reduced, and the hand consisting only 

 of two fingers about alike in size, and connected with each other at 

 the posterior ends. The carpal joint of the chelipeds in Atyoida is 

 longer than in Atya, especially on the second pair of legs. 



a^. Rostrum dentate below. Carpal joint of the first pair of pereio- 

 poda longer than broad A. potimirim. 



«2. Rostrum not dentate below. Carpal joint of the first pair of 

 pereiopoda not longer than broad A. bisulcata (many). 



1. Atyoida potimirim F. Miiller, 1881. 



F. Miiller, Kosmos (Krause), IX, 1881, p. 117 flf, figs. 1-20. 



Geographical dlstrihidion : Brazil : Itajahy (F. Miiller). 



2. Atyoida bisulcata Eandall, 1839. 



Atyoida bisulcata Eandall, Journ. Acad. Nat. Sci., Philadelphia, VIII, 1839, 



p. 140, pi. 5, fig. 5. 

 Atyoida bisulcata Dana, U. S. Expl. Exp. Crust., 1852, p. 540, pi. 34, fig. 1. 

 Atyoida bis7t/cata Stimjison, Proceed. Acad. Nat. Sci., Philadelphia, 1800. p. 28. 

 Atyoida tahitensis Stimpson, ibid. 

 Atyoida bisulcata and tahitensis A. Milne-Edwards, Annal. Sec. Entomol., 



France (4), IV, 1864, pp. 151 and 152. 

 Atya bisulcata (Band.), Bate, Challenger Macrur., 1888, p. 700, pi. 120. 

 Alva bisulcata (Hand.), Sharp, Proceed. Acad. Nat. Sci., Philadelphia, 1893, 

 ' p. 111. 



Geographical distribution: Hawaiian Isl. (Kandall, Stimpson): 



Oahu (Dana, Sharp) ; Tahiti (Stimpson). 



ATYA Leach, 1317. 



Atys Leach, Trans. Linn. See. London, XI, 1815, p. 345 (nomen prEcoccupa- 



tum). 

 Atya Leach, Zoolog. Miscell., Ill, 1817, p. 29. 



ctj. Rostrum shorter than the antenuular peduncle, without teeth on 



the upper margin [Subgenus J ^^a]. 



6i. Rostrum without lateral keels and without lateral teeth 

 near the base. 

 Cj. Rostrum longer than the first joint of the antennulse, 

 horizontally projecting or sometimes bent upward. 



A. moluGcensis (6). 



Cj. Rostrum as long as or shorter than the first joint of 

 the anteuuuhe, bent downward. A. spinipes^^ (12). 



" A. spinipes might be regarded as a variety of A. moluccensis. 



