174 PROCEEDINGS OF THE ACADEMY OF [1895. 



Crangonidie are connected with the Nikidse by the genus Glypho- 

 crangon, but this connection is not a close one — there are some 

 gaps. 



Among the Crangonidre, the genus Pontocaris is no doubt the most 

 primitive in regard to the sculpture of the carapace; the number oi 

 gills and the shape of the second pair of pereiopoda. From Ponto- 

 caris arise two divergent branches: the one through the subgenus 

 Sclerocrangon to Crangon, ending in Nectocrangon, characterized b) 

 no shortening of the second pair of pereiopoda, by the reduction o: 

 the number of gills, and by the surface of the body becoming grad- 

 ually smoother. The other branch is represented by the genera 

 Pontophilus, Sabinea, Paracrangon, characterized by the reduction of 

 the second pair of pereiopoda in length, by retaining the primitive 

 number of gills and the sculpture of the body. In Pontojjhilus some 

 species have the body more or less smooth. The genus Prionocrangon 

 is an aberrant one, without eyes, but related probably to the genera 

 Pontophilus and Sabinea of the second branch. 



CRANGONIDJE Bate, 1888. 



Crangonince Kingsley, Proceed. Acad. Nat. Sei. Philadelphia, 1879, p. 411. 

 CrangonidcE Bate, Challenger Macrur., 1888, p. 481, Ortmann, Zoolog. Jahrb., 

 V, 1890, p. 462. 



Mandibles simple, slender, incurved, not dilate or bifid, without a 

 synaphipod. First pair of legs stouter than the second, hand sub- 

 chelate, the dactylus closing on the margin of the palm, the pollex 

 being spiniform. Second pair of legs very feeble, chelate, often 

 shortened, not chelate, or wholly reduced. External maxillipeds 

 pediform. Maxillae with more or less reduced innermost parts. 

 Rostrum mostly short. 



a x . Second pair of legs present. 

 b x . Eyes present. 

 g x . Second legs not remarkably shortened (carpal joint and hand 

 together longer than the merus). Gills seven on each side. 

 Carapace with dentate longitudinal keels .... Pontocaris. 

 c 2 . Second legs not shortened. Gills five on each side. 

 d x . Eyes free. Dactyli of the two posterior pairs of legs not 



dilated Crangon. 



d 2 . Eyes nearly hidden by the frontal part of the carapace. 



Dactyli of the two posterior pairs of legs dilated, natatorial. 



' Nectocrangon. 



