48 CALIFORNIA ACADEMY OF SCIENCES. 



Carapace usually wide, undulated above. Hepatic regions depressed. 

 Front flattened, produced into five, generally obtuse teeth which lie in the 

 same horizontal plane, the outermost pair not more widely separated from 

 the inner pair than these are from the median tooth. Superior margin of 

 the orbit between the two fissures not produced into a tooth, as in anten- 

 narius; external orbital tooth small, the next one behind it rounded; suc- 

 ceeding teeth becoming larger and more acute posteriorly, the last tooth, 

 in adult specimens, being the largest. Between the teeth the margin of 

 the carapace is marked with short, closed fissures. The tooth on the 

 lower margin of the orbit small or absent. Flagellum of the antennules 

 considerably shorter than the width of the front. Merus of the maxilli- 

 peds obliquely truncated at the distal end and notched on the inner side 

 at the articulation of the palp. Carpus of the chelipeds with a large tooth 

 at the antero-iuternal angle and a smaller one behind the upper hinge 

 joint; the outer surface is roughened with several irregular prominences; 

 hand with a double row of tubercle-like teeth on the upper edge and four 

 or five granulated costse on the outer surface, the upper ones of which are 

 the most obscure; fingers stout and tipped with black, the dactyl not 

 cristate above. Ambulatory legs nearly naked, except the dactyls which 

 are slender and a little longer than the propodi. Terminal abdominal 

 segment in the female nearly equilaterally triangular, the sides concave. 

 In the male this segment is more narrowly triangular than in the other 

 sex. Color dark reddish above; below a dirty white. 



Length of large specimen, male 85 mm. 



Breadth of large specimen, male 131 mm. 



Length of small specimen, female 22.5 mm. 



Breadth of small specimen, female 33.5 mm. 



Dr. Stimpson has given a table of measurements of 

 specimens of different sizes and sex, showing that the 

 males are wider than the females and the old males rel- 

 atively wider than the young ones. The proportion of 

 length to breadth was found to vary from 1:1.30 in a 

 male .99 in. in length to 1: 1.63 in a male of 2.95 in. in 

 length. The young of this species differ in many 

 respects from the old specimens. The carapace is much 

 flatter and smoother, and ornamented above with 

 numerous longitudinal, colored lines which entirely dis- 

 appear in the adult. The teeth of the front are repre- 

 sented by five subequal crenulations. The teeth on the 

 antero-lateral margin are much less distinct, being 



