1879.] NATURAL SCIENCES OF PHILADELPHIA . 419 



ensiform, not articulated to the carapax ; antennulse biflagellate; 

 external maxillipeds slender; first pair of feet short, equal ; second 

 pair slender; carpus multiarticulate. Type Hippolyte spinus 

 (Sowerby sp.). 



Genus Caridion Goes. 1 Rostrum elongate, cult rate ; mandibles 

 with a three-jointed palpus : antennuhe biflagellate ; first two pairs 

 pereiopoda nearly equal, chelate, carpus of the first pair very short; 

 of the second elongate, obsoletely Inarticulate. Type Caridion 

 gordoni (Spence Bate sp.). 



Genus Bythocaris G. 0. Sars. 2 Rostrum very small, simple, 

 unarmed ; antennuhe biflagellate; antennal scale large and broad ; 

 external maxilliped with the last joint dilated, obliquely truncate, 

 and armed with teeth, a minute exognath present. First pair of 

 feet as in Hippolyte; second pair slender, weak; carpus multiar- 

 ticulate. Type Bythocaris simplicirostris G. 0. Sars. 



Genus Cryptocheles G. O. Sars. 3 Rostrum small, narrow, 

 toothed above; antennulse biflagellate; antennal scale large, ex- 

 ternally dentate; last joint of external maxillipeds with the apex 

 somewhat bipartite, a small exognath present. First pair of 

 pereiopoda very short; hand very elongate and attenuate, digits 

 very short, and with difficulty visible ; second pair slender; car- 

 pus 7-jointed. Type Cryptocheles pygmsea G. 0. Sars. 



o Genus Rhynchocinetes M. Edw. Resembling Hippolyte. Ros- 

 trum ensiform, movable, articulated to the carapax; antennulse 

 biflagellate; carpus of second pair of pereiopoda not jointed. 

 Type Rhynchocinetes typus M. Edw. 



Genus Ogyris Stm. 4 Carapax not rostrate, or with rostrum 

 very small, as in the genus Alpheus. Eyes very long; antennuhe 



in the Arcbiv fur Naturgeschichte, 1846, pt. 2, p. 310-811, says that there 

 are no points mentioned by Costa which would not apply to Hippolyte. On 

 the other hand Heller (Crustaceen des siidlichen Europa, p. 2o6, 1863) re- 

 gards one of Da Costa's species (P. elegant) as belonging to the genus An- 

 ehistia of Dana For remarks on the synonymy of Hippolyte and that of 

 Virbius, attention is called to Smith, Trans. Conn. Acad. v. pp. 62 and 63, 

 1879. 



1 (Efversigt af K. Vetensk. Akad. Forhandl. 1863, p. 170. Doryphorus 

 Norman, Ann. et Mag. Nat. Hist. 3d series, viii. p. 276, 1861 mom. prseoc). 



2 G. O. Sars, Saerskiltaftryktaf Vidensk. Selsk. Forhandlinger, p. 5, 1869. 



3 Vidensk. Selsk. Forhandlingar, p. 150, 1868. 



4 Stimpson, Proc. Acad. Nat. Sci. Philadelphia, 1860, p. 36. 



