58 RATHBUN 
E. Rostrum less than twice as long asthe eye washingtoniana. 
E’. Rostrum twice or more than twice as long as the eye. 
F. Antennular scale shorter than first segment of peduncle 
vicina. 
F’. Antennular scale longer than first segment of peduncle. 
G. Fifth segment of abdomen not armed with a spine on 
either side. -  affinis. 
G’. Fifth segment of abdomen ‘armed with a spine on 
either side. 
H. Rostrum longer than the rest of the carapace 
unalaskensis. 
H’. Rostrum no longer than the rest of the carapace 
polaris. 
A‘. No supraorbital spine or spines. 
B. Rostrum about as long as or longer than the rest of the carapace. 
C. Third, fourth, and fifth segments of abdomen carinated, the carina 
on each segment terminating in a sharp spine . . darbata. 
C’. Third, fourth, and fifth segments not all carinated nor ending in 
a sharp spine. 
D. Terminal half (at least) of rostrum devoid of spines above. 
E. Third abdominal segment with an angle or hump, in profile, 
toward the posterior end. 
F. More than 3 dorsal teeth, one or more in front of eyes. 
G. Sixth abdominal segment less than twice as long as 
wide. Rostrum deep, one fourth as deep as long 
carinala, 
G’. Sixth abdominal segment more than twice as long as 
wide. Rostrum more slender. 
H. Maxilliped with epipod. Scale at base of antennula 
extending beyond first segment. . . . flexa. 
H’. Maxilliped without epipod. Scale at base of an- 
tennula not reaching poate or only slightly 
beyond, first segment . . sp seraciis: 
F’. Three dorsal teeth, none in front of eyes oF Nios REZELCHS. 
E’. Third abdominal segment smoothly rounded, without angle 
or hump. 
F. One or more superior rostral spines in front of eyes. 
G. No pterygostomian spine . . . . « « « stylus. 
Gi A pterygostomian spine oun ct m Qmabiles: 
F’. No superior rostral spine in front of eye sims Saori. 
D’. Terminal half of rostrum with spines (in part at least). 
E. Terminal third of rostrum unarmed above and below 
biunguis. 
E’. Terminal third of rostrum not entirely unarmed. 
F. Sixth abdominal segment longer than seventh . decora. 
F’, Sixth abdominal segment shorter than seventh. 
G. Maxilliped exceeding acicle. 
H. Rostrum straight above. Epipods on maxillipeds 
and first two thoracic feet. . . . paludicola. 
