108 CALIFORNIA ACADEMY OF SCIENCES. 



This is one of the most common of our California 

 crabs and is generally found under rocks at low tide. 

 According to Ortmann (I.e.) "Die in Philadelphia 

 aufbevvahrten Originale Randall's zeigen, dass cinctipes 

 dieselbe Art ist wie rupicola. Der von Randall ange- 

 gebene fundort ' Sandwich-Ins.' beruht offenbar auf 

 der unter seinem Material vorgekommenen Verwechs- 

 lung der Localitaten." I am unable to follow Ortmann 

 in uniting eriomerus St. with this species. The two 

 forms occur together on a great part of the California 

 coast and keep perfectly distinct. 



Petrolisthes eriomerus St. 



Petrolisthes eriomerus STIMPSOX, Ann. N. Y. Lye. Nat. Hist., Vol. X, p. 

 119. LOCKINGTON, Ann. Nat. Hist. (5), Vol. II, 1878, p. 397. 



Closely allied to cinctipes. Carapace smooth and punctate, though there 

 are often minute prominences, especially anteriorly, which are not so 

 marked as in the preceding species. Front not so strongly deflexed as in 

 cinctipes. The antennae may be over twice the length of the carapace and 

 are devoid of setae. Distal, extremity of the ischium of the maxillipeds 

 more or less truncated. Chelipeds longer and smoother than in cinctipes; 

 the carpus is narrower and has the sides parallel; the antero-internal angle 

 is much less prominent and the ridge on the posterior margin rougher. 

 The merus joints of the ambulatory legs are hairy and less dilated than in 

 the preceding species. The last pair of sutures on the telson is trans- 

 verse or nearly so. 



Hurnboldt County, Calif., to San Francisco Bay! 

 Point Mendocino (Stimpson)! I have collected numer- 

 ous species at the latter, or type locality. Cinctipes is 

 also abundant in the same place. 



Genus Pachycheles Stimpson. 



Carapace round-ovate, or suborbicular, and not longer than wide, the 

 posterior portion of the subbranchial region subquadrate and separated 

 from the larger anterior portion by a membranous interval. Front but 

 little produced, subacute, edentulous. First joint of theantennal peduncle 



