50 BULLETIN 138^ UNITED STATES NATIONAL MUSEUM 



increasing in height from proximal to distal end, where a rounded 

 lobe projects over the dactylus. Both fingers are a dark bluish- 

 black except at the proximal end (British Columbia, Xo. 141) ; their 

 horizontal length is less than the middle length of the palm; they 

 are inclined gently downward, the tips curving toward each other 

 and crossing ; there are a few longitudinal rows of punctae ; the long- 

 est tooth is at the base of the dactylus, succeeding teeth few and very 

 shallow, lobiform; teeth or lobes on fixed finger five in number, 

 diminishing in size toward extremity of finger. 



The chelipeds of the female (pi. 13, fig. 3) are smaller in propor- 

 tion to the size of the carapace than those of the male, and the palms 

 are shorter and more rotund, not highest at the distal end (Wash- 

 ington, Nos. 187 and 253). 



Ambulatory legs: These are long and slender (No. 253), differing 

 little in length. The coxa and ischium are granulate near the distal 

 end. The merus is long, narrow, compressed, its cross-section two- 

 thirds as wide in its widest part as it is long, outer surface nearly 

 smooth, a shallow furrow through the middle of the flat, posterior 

 surface. The propodus is about half as long as the merus, its median 

 furrow is deeper; the carpus is a little shorter than the propodus. 

 The dactylus is probabl}^ about as long as the carpus, but the ends 

 of all of them are lacking; the median groove is deeply impressed. 



Measurements. — Width of carapace of type-specimen 49 mm. 

 Length of carapace in the median line (Oregon, No. 15) 37 mm., 

 width 45.4 mm. Length of another from the same place 36.2, width 

 42.5 mm. The largest carapace (Washington, No. 253) is about 74 

 mm. wide. The largest nodule containing a crab (Oregon, No. 948) 

 has a major diameter of 19 cm. 



Relation. — This species is nearest to the type species of the genus, 

 Z. leachii (Desmarest, 1822; A. Milne Edwards) ^^ which also has 

 a nodose carapace and four antero-lateral lobes of moderate size, but 

 in leachii the posterior half of the branchial region is occupied by 

 tvro small nodules instead of one large one as in vulgaris., and the 

 epibranchial nodule is small and round instead of obliquely trans- 

 versely elongate. In leachii the antero-lateral is longer in relation to 

 the postero-lateral margin than in vulgaris. 



Occurrence. — From the southern border of Vancouver Island, 

 British Columbia, along the Strait of Juan de Fuca and southward 

 along Puget Sound, thence eastward to Burnett and westward to 

 Chehalis County, Washington, thence southward across the Columbia 

 River to Lincoln and Lane Counties, Oregon. 



The species appears to be distributed throughout the Oligocene 

 and to be confined to that series. 



•T Ann. Sci. Nat., ser. 4, Zo61., vol., 20, 1863, p. Slo, pi. 7, figs. 1 and 2 ; pi. 8, figs. 3 

 and 4 ; pi. 11, fig. 4. 



