THE SPIDER CRABS OF AMERICA 243 



than in opilio. The lateral margin of the carapace is deeply scalloped* 

 this character alone serves to distinguish very young specimens (10 

 mm. and under) from the allied species. Chelipeds and legs more 

 coarsely and abundantly spinous than in the allied species. Male 

 abdomen with sides a little more concave, terminal segment with its 

 free edge more arched, the segment less invaginated in the preceding 

 segment. 



Measurements. — Male holotype, length of carapace and rostrum 

 73.3, width 81.2, length of cheliped about 100, of first ambulatory leg 

 about 182 mm. Male (31661), length of carapace and rostrum 121, 

 width 139.4, length of cheliped about 197, of first ambulatory leg, 

 292 mm. 



Range. — From the southeastern part of Bering Sea (lat. 56° 18' 00" 

 N.) and the Aleutian Islands (about long. 178° E.) eastward and south- 

 ward to British Columbia (Kingcombe Inlet). From shallow water 

 to 259 fathoms; usually in less than 100 fathoms. 



Material examined. — See table, pages 244-246. 



CHIONOECETES TANNERI (Rathbun) 



Plates 88, 89, and 234 



Chionoeceles tanneri Rathbun (part), Proc. U. S. Nat. Mus., vol. 16, 1893, 

 p. 76, pi. 4, figs. 1-4 (type-locality. Gulf of the Farallones, California, 29 

 fathoms; holotype. Cat. No. 15860, U. S. N. M.); Harriman Alaska E.k- 

 ped., vol. 10, 1904, p. 174. — Holmes, Occas. Papers Calif. Acad. Sci., 

 vol. 7, 1900, p. 40. — Weymouth, Leland Stanford Jun. Univ. Publ., Univ. 

 Ser. No. 4, 1910, p. 35, pi. 7, fig. 19. 



Diagnosis. — Carapace chiefly spinose. Rostrum ascending. Bran- 

 chial regions nearly meeting on median line, interspace deeply de- 

 pressed. Lateral margin of carapace exposed in dorsal view only as 

 far forward as third pair of ambulatory legs. Meropodites of legs 

 narrow, little dilated. 



Description. — Carapace much swollen at the branchial regions, 

 which are distended both vertically and laterally, concealing the lat- 

 eral margin of the carapace. Between the branchial regions, which 

 nearly meet, there is a deep, narrow depression which Avidens ante- 

 riorly and joins the cervical suture. Carapace covered with spines 

 and spinules instead of tubercles and granules; the transverse row 

 across the branchial regions is more prominent than in opilio, and is 

 well in advance of the cardiac row; from its outer end a row of spines 

 runs obliquely forward toward the orbit. The outer spine of the 

 oblique branchial row is as large as the outer spine of the transverse 

 row, is directly in front of it, and is usually more produced laterally; 

 the two rows therefore join in a curve not at an angle. Another row 

 of spines forms the lateral supra-marginal border of the branchial 

 region, and is continued on the pterygostomian region; from this row 



