274 University of California Publications in Zoology [Vol- 23 



Biological Survey of San Francisco Bay. — Hemigrapsus nudus is 

 a strictly littoral species, recorded only from the middle bay, doubtless 

 because all shore collecting was confined to that section. Specimens 

 from one to a dozen or more were obtained at Point Bonita, along the 

 Presidio shore, at Sausalito, north of the Key Route pier, on Red 

 Rock, and in tide pools along the Richmond shore, north of the 

 Standard Oil pier. 



Hemigrapsus oregonensis (Dana) 

 Plate 48 



Pseudograpsus oregonensis Dana, Proe. Acad. Nat. Sci. Phila., 5, 248, 1851 ; 

 Crust. U. S. Expl. Exped., 1, 334, 1852, pi. 20, fig. 6, 1855. 



Heterograpsus nudus Bathbun, E., The Fisheries and Fishery Industries 

 of the U. S., sec. 1, p. 765, 1884. 



Brachynotus oregonensis Holmes, Occas. Tapers Calif. Acad. Sci., 7, 82, 

 1900. 



Hemigrapsus oregonensis Eathbun, H. A. E., 10, 189, 1900; Weymouth, 

 Stanford Univ. Publ., Univ. Ser., no. 4, 63, pi. 14, fig. 43, 1910; Eath- 

 bun, Bull. U. S. Nat. Mus., 97, 270, pi. 70, 1918. 



WV 



Fig. 162. Hemigrapsus oregonensis, outline of front, X % (after Dana). 



Characters. — -Carapace more strongly undulated in front than in H. nudus, 

 but not so much flattened behind; posterior portion not punctate, and anterior 

 portion may be sparsely granulate; front with a deep sinus in the middle, front 

 four-lobed, the median lobes the most prominent. Chelipeds smooth, not spotted 

 with red; in the adult male there is a rounded lobe on the antero-internal angle 

 of the merus, and a patch of long hair on the inner surface of the hand. Ambula- 

 tory legs hairy; dactyls narrower than in H. nudus, those of the last pair 

 upturned. 



Dimensions. — Type: length of carapace 21.2 mm., width 24.4 mm. The Bay 

 specimens ranged from 3 to 29 mm. in width of carapace, the greater number being 

 about 20 mm. wide. 



Color. — In life a light grey, with minute blackish or dark blue spots, which 

 are more numerous in some regions than in others. Legs lighter, marked with 

 similar spots; hands of chelipeds whitish in tone, without spots (Weymouth). 



Type Locality. — Puget Sound. 



Distribution. — From Prince William Sound, Alaska, to Gulf of California 

 (Eathbun). 



Bernards. — This species may be readily distinguished from the preceding by 

 its dull color, hairiness of the legs, the four-lobed front, and absence of round 

 red spots on the chelipeds so characteristic of that closely related species 

 (Holmes). 



