148 University of California Publications in Zoology [Vol. 23 



2. Ambulatory legs considerably longer than greatest width of carapace, 

 often about twice or nearly twice as long. 



a. Abdomen well calcined, median row of plates of segments three to 



five replaced by a membranous area well armored with 

 numerous spiny, calcified nodules. Carapace more or less 

 strongly spined, not less than four sharp-pointed spines on 

 gastric region, 

 i. Plates of basal (second) abdominal segment distinct, sep- 

 arated by sutures. (Known only from 155 -f- fathoms.) 



Paralithodes, p. 160. 



ii. Plates of basal (second) abdominal segment more or less 



fused, either completely so, or with median and lateral 



or lateral and marginal plates fused together. (Known 



only from 301 + fathoms.) 



Lithodes, p. 161. 



b. Abdomen more or less leathery, median row of plates of seg- 



ments three to five distinct and separate; basal (second) 

 segment entire. Upper surface of carapace more or less 

 tuberculated or covered with numerous short, blunt spines, only 

 one sharp spine on gastric region. (Known only from 625 -f- 

 fathoms.) 



Paralomis, p. 158. 

 The genera of this family are for convenience divided into two groups, based 

 primarily on the character of the abdomen, corresponding to the major divisions 

 of the above key (Brandt, 1850, p. 259; Bouvier, 1896a, p. 16). The apparent 

 basal segment of the abdomen is in reality the second, while the last, or terminal 

 (ultimate) segment, or plate represents the telson. 



I. Abdomen soft, more or less loosely inflexed, unsegmented; at most only basal 

 (second) and two terminal segments, stiffened by thin calcareous plates; 

 reinforcement of basal segment usually consisting of a pair of narrow 

 marginal plates and a pair of lateral plates, between wMch there may be 

 a median plate; abdomen occasionally armed with calcified granules or short 

 spines. Carapace more or less distinctly flattened, occasionally slightly but 

 never strongly convex, lyrate or roughly quadrilateral; front moderately 

 broad; rostrum scarcely if at all exceeding the eye-stalks. (Group II, 

 p. 153.) 



Genus Hapalogaster Brandt 



Carapace, chelipeds, and ambulatory legs much flattened and more or less 

 hairy or pubescent; lateral margins of carapace with a few small teeth or spines. 

 Basal (second) abdominal segment with a thin, transverse, calcareous lateral plate 

 on either side; a pair of marginal plates present but small and inconspicuous. 



Key to the California Species of Hapalogaster 



I. Hand of larger cheliped densely covered with short hair, somewhat roughened or 

 granulated at the insertions of the hair, not spinous or tuberculated except 

 for one or more small calcareous tubercles on inner face, behind articulation 

 of the dactyl. Lateral margins of carapace with not more than two small 

 teeth on each side. (From Cape Mendocino to Monterey.) 



cavicauda, p. 149. 



