36 Addison E. Verrill, 



EE. First pair of legs not chelate; second pair more slender, chelate, 

 with the carpus divided into numerous articles. Rostrum elongated 

 and usually serrate, sometimes movably articulated with the carapace; 



mandibles have a jointed palpus. 



Family Pandalidce. 



CC. Second pair of legs usually larger than the first, with the carpus not 

 subdivided, and the chelae larger than those of the first pair, often much 

 larger. 



H. Third maxillipeds more or less leg-like, with the articles not greatly 

 dilated nor operculiform. 



I. Rostrum elongated and usually serrated on one or both edges ; second 

 pair of legs commonly very much longer and larger than the first ; 

 both pairs chelate ; base of antennules excavated above, and usually 

 with a scale. Eyes large, usually with a small accessory ocellus. 



Mandibles with or without a palpus. 



Family Pal&monidce. 



I, I. Rostrum usually small, not serrate, sometimes lacking, sometimes 

 (as in Perlclimenes') elongated and serrate; first pair of legs usually 

 equal ; one chela sometimes much enlarged ; all legs without exopods 

 or mastigobranchs ; mandibles have no palpus ; third maxillipeds 

 often with some articles widened, more or less. Many species are 



commensals with Mollusca, etc. 



Family Pontonidce. 



H, H. Third maxillipeds with the third article much dilated or operculi- 

 form, the pair completely covering the oral area. Chelae equal in both 

 pairs ; second pair larger ; rostrum short serrate above ; mandibles 



simple without a palpus or cutting edge. 



Family Gnathophyllidcc. 



Tribe STENOPIDEA Bate, 1888. Oceanic Shrimp. 

 Stcnopidea Stebbing, History of Crustacea, p. 211, 1893. 



Three anterior pairs of legs are chelate; those of the third pair 

 are the largest and longest; fourth and fifth pairs have the carpus 

 subdivided. Branchiae are filamentous. Appendages of the first 

 segment of the pleon are unbranched and differ little or not at all 

 in the sexes. Podobranchise are lacking, except on the first pair 

 of maxillipeds. Mandibles have a three-branched palpus. 



Family STENOPID^ Huxley, 1883. 



Stenopida A. M.-Edw. and Bouvier, Mem. Mus. Comp. Zool., vol. xxvii. 

 The characters of the family are the same as for the tribe above. 



Stenopus hispidus (Oliv.) Latr. 



Palcemon hispidus Olivier, Encyc. Meth., Insects, vii, p. 666, 1811, pi. 319, 

 fig. 2, 1818. 



