1917 Wai/j on Taaonomi/ of Crabs 359 



2. Hemigrapsus oregonensis (l)aiia) R.itlibim. hairy shore crab (fig. 8) 

 Pseudograpsus oregonensis Dana; Brachynotus oregonensis Holmes. 



Very similar in general eharacteristics to //. nudus. Carapace of the 

 same general shape with the characteristic smooth and punctate surface; 

 front with four lobes, the median ones being more prominent; the promi- 

 nences behind the front are more noticeable than in //. nudus. There is 

 the same H-shaped depression with white pits extending in a curved line 

 to the last antero-lateral tooth; the ridge on the pterygostomian region 

 has fewer but larger teeth. Chelipeds large and smooth with the exception 

 of the merus which has a row of fine hairs on the upper and lower edges 

 of the inner side; the flat rounded projection on the distal end of the 

 merus and the rounded projection on the inner side of the carpus are 

 both present; males have a patch of soft hairs on the inside of the hand; 

 dactyl and pollex somewhat roughened on the inner edge but no prominent 

 well defined teeth. Walking legs hairy, particularly on up))er margins; 

 dactyls grooved, with rows of short liairs between ridges; more slender 

 than in //. nudus. Color gray with bluish-black markings; the walking 

 legs have numerous groups of tiny s})ots, while the carapace is more or less 

 mottled with larger blotches of color; ventral surface of hands and dactyls 

 very much lighter in color, dirty white. 



More or less variation of color was observed in these, especially 

 among the smaller specimens. As in //. nudus, some are almost wholly 

 white. Many of these small mottled ones were bearing eggs, and varied 

 in width from 8 to 12 mm. And in length from 7 to 10 mm. These were 

 collected from June 25 until July 1. The largest specimen collected 

 measured .SI mm. wide and 28 mm. long. 



The coast line from Point Caution (1) to Argyle Bay (14) on San 

 Juan Island was carefully examined and //. oregonensis was found abund- 

 antly on the fine sandy and muddy portions of the coast line, but it became 

 less abundant as sandy and muddy flats merged into rocky portions and 

 finally disappeared altogether; Newhall's Lagoon (6), Argyle Lagoon (13) 

 and McDonald's beach (3) contained great numbers of them. 



Family PINNOTHERIDAE 



KEY TO GENERA 



A. Dactyls of last i)air of walking legs markedly longer than those of 

 preceding pair. pinnotheres (p. 360) 



AA. Dactyls of last pair of walking legs not longer than those of pre- 

 ceding pair. 



