20 Crustacea and Echinodermata of the 



cancer gracilis. Dana. 



Cancer gracilis, Dana; U. S. Exploring Expedition, Crust, i. 153, PL VII. f. 2. 

 Stimpson ; Proc. Cal. Acad. Nat. Sci. i. 88. 



This is the smallest species of the genus known, although 

 found of a much larger size than that figured by Dana. It 

 may be distinguished from the young of C. magister by the 

 emargination or slight tooth on the postero-lateral margin 

 near its outer extremity, as well as by its proportions. It 

 differs from C. irroratus, ( C. Sayi, Gould,) which also pos- 

 sesses the postero-lateral emargination, by its smoother and 

 more slender tarsi, and by the granulation of the central 

 portions of the carapax. The antero-lateral margins are 

 nine-toothed. Lateral teeth of inter-antennary front deeply 

 separated from, and much larger than, the middle one, 

 although not projecting so far forward. Third article of 

 outer maxillipeds smooth, with the exterior apex rounded. 

 Terminal segment of abdomen in the male elongate-trian- 

 gular, with a slender, pointed extremity. The following 

 are the dimensions of several specimens now before me : — 



Proportion. 



1:1.52 inch. 



1:1.50 



1:1.50 



1:1.47 



1:1.47 



We may thus notice that in this species the males are 

 wider than the females. 



Puget Sound, (Suckley;) Tomales Bay, (Samuels;) San 

 Francisco Bay, (Expl. Exped.) 



Mas. Expl. Exped. ; Smithsonian ; Bost. Soc. ; Phil. 

 Acad. ; Acad. Petrop. ; Paris ; etc. 



Locality. 



Sex. 



Tomales Bay, 

 ii i< 



$ 



ii ii 



Puget Sound, 



it 



9 



Tomales Bay, 



" 



Length of 

 Carapax. 

 1.51 inch. 



Breadth of 

 Carapax. 

 2.30 inch. 



1.60 



2.40 



1.70 



2.55 



1.90 



2.80 



1.45 



2.13 



