ISOPODS OF NORTH AMERICA. 37 



Family II. APSErDID.E." 



Body attenuated behind. First pair of antennte with two inieqnal 

 multiarticulate llaoella. Second pair of antenna? usually furnished with 

 a scale at the end of the second article of the peduncle. Mandibles with 

 palp. Anterior niaxilhe with two masticatory lobes. Posterior max- 

 illa' well developinl and setose. Epi^nath of maxillipeds large, lam- 

 inar, branchial in character. Two anterior pairs of legs, usually 

 provided at the base with minute, two-jointed exopods (exopodites). 

 Second pair of legs fossorial in character. Uropoda double-branched; 

 branches multiurticulate. 



ANALYTICAL KEY TO THE GENERA OF APSEUniD;!?. 



a. Second pair of aiiteniiit' with a scale articulated to the end f)f the second article. 

 Head and first thoracic- segment coalesced. 

 h. Exopods present on both pairs of gnathopods. 



r. Five pairs of pleopoda present, with branches uniarticnhite. Abdomen com- 

 posed of six segments Genus Apseudes Leach 



c/. Only four pairs of -pleopoda present, with one of the branches two-jointed. 



Abdomen composed of six segments Genus Parapseudes Sars 



//. Exopods absent on both pairs of gnathopods. Five pairs of pleopods present, 

 in which one of the branches is two-jointed. Eyes absent. 



(jienus 7)fp}daj>seudes Beddard 



a^. Second pair of antennte without a scale. Head and first two thoracic segments 



coalesced. Eyes absent Genus Sphyrapus Norman and Stebbing 



8. Genus APSEUDES Leach. 



Second antennw with a scale articulated to the end of the second 

 article. Exopods present on both pairs of gnathopods. Five pairs 

 of pleopoda present, in which the branches are uniarticulate. First 

 pair of legs in male larger than in female. First pair of antennae 

 usually alike in the two sexes. 



AXALVTICAL KEY TO THE SPECIES OF THE GENUS APSEUDES. 



a. Head with rostrum short, produced to a mere point. Body without spiny arma- 

 ture. Flagellum of tirst antenna of same length as secondary filament. 



Apseudes esp'uiosus Moore 



a\ Head with distinct rostrum. Body with spiny armature. Secondary appendage 



of first antenna shorter than tiagellum. 



/*. Basal article of peduncle of first antenna unarmed. Secondary appendage of 



first antenna one-fourth as long as flagellum. Long spiny processes on either 



side of head, one pair at the place of fusion of the first thoracic segment with 



the head, the other pair anterior to these, being the produced outer angles 



of the ocular lobes. Last segment of abdomen with posterior margin slightly 



emarginate, a small lobe being placed in the center of the emargination. 



Apseudes gracilis Norman and Stebbing 



"See Sars, Crust, of Norway, II, 1899, p. '^, and Norman and Stebbing, Trans. 

 Zool. Soc, London, XII, 1886, p. 79, for characters given below. 



