140 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.21 



among Hancock collections is due largely to the activity of Charles Wade 

 and Fred Ziesenhcnne, who visited the Oregon coast in 1942, and Dr. 

 John L. Mohr, who visited the San Juan Islands in 1948 and 1949, 

 preparing the way for later exchanges of specimen material. 



The male first pleopod, here described, is figured by Shen (1932, 

 fig. 25a and c). 



Oregonia bifurca Rathbun 

 Plate I, Fig. 1 ; Plate 11, Fig. 2 



Oregonia bifurca Rathbun, 1902a, p. 885; 1904, p. 171, pi. 6, fig. 5; 

 1925, p. 79, pis. 26-28, text-fig. 21. 



Type: Female holotype, U.S.N.M. No. 25287, length 26.5 mm, 

 width 19.6 mm. 



Type locality: North of Rat Island, Aleutian Islands, 270 fathoms, 

 Albatross station 3785. 



Localities subsequently reported, ivith collectors: Bowers Bank, 

 Bering Sea, 344-764 fathoms, Albatross (Rathbun, 1925). 



Atlantic analogue: None. A Pacific boreal species. 



Diagnosis: Rostrum composed of two short, flattened, divergent 

 spines. Postorbital spine close to eye, triangular, and directed more for- 

 ward than outward. Carapace subquadrilateral, hepatic narrowing im- 

 perceptible. Chelipeds of male little longer than first pair of walking 

 legs, spinulous; fingers nearly as long as palm. Dactyls of ambulatory 

 legs long. A hairy species. 



Male first pleopod with tip swollen, little inclined, bearing a row of 

 five long filaments on one side of a line extending backward from the 

 aperture, a row of seven on the other side at the same level ; behind these 

 at a higher level 1 1 more filaments arranged in two rows. 



Description: Carapace about three- fourths as wide as long (rostrum 

 included) ; width between tips of postorbital spines two-thirds of the 

 branchial width. Branchio-hepatic constriction very slight. Surface of 

 carapace covered with tubercles from which proceed long yellow hairs, 

 curved at the tips, making a tolerably thick coating. Rostrum not divided 

 quite to the base; horns slender, divergent, their outer margins almost 

 longitudinal, their length along the inner margin about one-eighth of the 

 entire length of the carapace. Supraocular eave extending laterally not 

 quite so far as in Oregonia gracilis. Postocular spine narrow, as in O. 

 gracilis, and directed a little more forward than in that species. Inter- 

 antennular spine curved a little more forward than in O. gracilis. Eyes 

 a little stouter than in that species. Basal segment of antenna armed 



