THE CANCROID CRABS OF AMERICA 



157 



2 cardiac, and 2 branchial. Crescentic furrows at center of carapace 

 deep. Margins denticulate. The two frontal teeth are broad, each 

 tipped with an acute denticle; in the young, however, there are two 

 extra teeth, one each side of the median line; eventually their tips 

 break off, leaving between the outer teeth a transverse margin broken 

 by the median suture. Inner orbital tooth narrow, acute. The 

 fourth lateral tooth of the carapace is midway of its length, is very little 

 larger than the preceding but projects farther laterally; the next three 

 teeth are small, but the sixth is larger than the other two. 



Chelipeds spinous; 6 longitudinal row^s of spines on the outer-upper 

 surface of the palm, two rows continued part way on each finger. 

 Ambulatory legs thick, armed with stout spines, which are longer and 

 stronger on the last three articles where they border each side of the 



a 



Figure 24.— Erimacrus isenbeckii. a. Female abdomen and sternum, b. Epistome. 

 c. Bristle from carapace, enlarged. After Benedict 



upper surface as far as the middle of the dactylus; a row of spines on 

 anterior surface of carpus and propodus, on lower margin of propodus 

 and base of dactylus. Dactyli tw^ce as long as propodi, having a deep 

 groove through the middle of each side, a finer groove higher up which 

 disappears toward the proximal end, and a superior groove broad and 

 shallow on the proximal half onl3^ The crab is hairy all over, the 

 hair longest on the maxillipeds, anterior sternum, inner surface of 

 chelipeds, and lower margins of legs. 



Measurements. — Male (47266), total length of carapace 127.6, 

 width of same 125, fronto-orbital width 70.7, width of front at base, 

 between antennae, 25 mm. 



Range. — From Cooks Inlet, Alaska, westward and northward to the 

 Pribilof Islands (Bering Sea) and Kamchatka, thence southward to 

 Korea and southern Japan. 



Material examined. — See table, pages 158-159. 



