160 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 21 



Diagnosis: Carapace spinulous, lateral margins partially concealed 

 by expanded branchial regions ; space between branchial regions shallow. 

 Rostrum inclined upward. Meri of ambulatory legs little dilated. A 

 large spine at angle made by the two dorsal branchial ridges. Male first 

 pleopod erect, tip acute, linear groove with a marginal row of about 17 

 filaments; a comb of 9 filaments on opposite side. 



Description: Carapace more pubescent than in Chionoecetes tanneri; 

 the pubescence of C. tanneri less dense and more easily rubbed off. 

 Posterior margin of carapace gently arcuate; in C. tanneri, a median 

 interruption or small shallow bight. Interbranchial space not so deeply 

 depressed; the urogastric region defined by a groove on either side; in 

 C. tanneri the whole region depressed and narrowly compressed. The 

 two dorsal ridges on the branchial region converging in straight lines and 

 meeting in an acute angle marked by a single, though not simple, large 

 spine; in C. tanneri the ridges meeting in a curved line marked by two 

 subequal spines. The posterior of these ridges formed of bunches of acute 

 tubercles, except that the outer one or two on each side may be spines or 

 spinous; in C. tanneri this ridge composed largely of single spines. 

 Rostral teeth wider, the width at base in half-grown specimens being as 

 great as the length of the inner margin; in old specimens, greater than 

 the length. 



Legs more dilated toward the proximal end. (Rathbun, 1925, modi- 

 fied) 



Material examined: From off Queen Charlotte Islands, British 

 Columbia, 876 fathoms, August 31, 1888, Albatross station 2860, 1 

 male, 1 female (U.S.N.M. No. 15478, part). The photographic illus- 

 tration is of the female. 



Measurements: Male specimen: length 24.6 mm, width excluding 

 lateral spines 23.3 mm, length of branchial spine 2.0 mm, rostrum 2.0 

 mm, width 4.0 mm, cheliped 27.3 mm, chela 11.7 mm, dactyl 8.0 mm, 

 ambulatory legs 61, 62, 59, and 44 mm, respectively. Female: length 

 26.4 mm, width 24.8 mm. 



Color in life: Unknown. 



Habitat: Green mud, fine black sand; Foraminifera noted. (Rath- 

 bun, 1925) 



Depth: 49-1,625 fathoms. (Rathbun, 1925) 



Size and sex: That males of the species attain a size comparable to 

 individuals of the Chionoecetes opilio-C. bairdi group is indicated by the 

 measurements given by Rathbun (1925): length along mid-line 134.4 

 mm, width without spines 151.5 mm, and length of first leg 356.6 mm. 



