142 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.21 



Genus HYAS Leach 



Hyas Leach, 1814, p. 431. Holmes, 1900, p. 31. Rathbun, 1925, p. 252. 



Type: The Atlantic Cancer araneus Linnaeus, 1758, by monotypy. 



Description: Carapace flattened, more or less tuberculated, but not 

 spiny. Rostrum bifid, flattened, the horns [separated] by a narrow fis- 

 sure. Orbits shallow and open above, with a fissure above and below. 

 Eyes partially visible from above when retracted. No preocular spine 

 [but a large, triangular postorbital tooth]. Basal antennal [article] much 

 enlarged, the [first movable article] moderately dilated, the [second] 

 narrow. Ambulatory legs subcylindrical and of moderate length. 

 (Holmes) 



Chelipeds stout, chelae compressed. (Rathbun) 



Abdomen with seven free segments in both sexes. 



Range: Eastern Pacific: from Bering Strait and the Aleutian Islands 

 to Puget Sound, Washington ; Western Pacific : from East Cape, 

 Siberia, to the Sea of Japan; Siberian, Alaskan, and Canadian Arctic; 

 Western Atlantic south to Cape Hatteras; Eastern Atlantic south to 

 English Channel. Shore to 350 fathoms; exceptionally (Western 

 Atlantic) to 906 fathoms. The distribution of both recent and fossil 

 species is reviewed by Imaizumi (1952, p. 179). 



Key to the Pacific American Species of Hyas 

 la. Posterior angle of hepatic projection broadly arcuate. Basal 



antennal article with a blunt tooth at anteroexternal angle 



coarctatus alutaceus 



lb. Posterior angle of hepatic projection subacute. Basal antennal 



article with a rounded tubercle at anteroexternal angle 



lyratus 



Hyas lyratus Dana 

 Plate I, Fig. 3 ; Plate 12 



Hyas lyratus Dana, 1851a, p. 268; 1852, p. 86; atlas, 1855, pi. 1, figs, 

 la-d. Stimpson, 1857b, p. 450. Lockington, 1877c, p. 64. New- 

 combe, 1893, p. 20; 1898, p. 76. Rathbun, 1893a, p. 72, pi. 3; 

 1904, p. 174; 1925, p. 270, pi. 235, text-fig. 90c. Caiman, 1898, 

 p. 260. Holmes, 1900, p. 32. Lenz, 1901, p. 454. Taylor, 1912, 

 pp. 191, 209. Way, 1917, p. 371, fig. 26. Johnson and Snook, 1927, 

 P. 372, fig. 325. G. M. Smith, 1928, pp. 164, 165. Hart, 1940, 

 P. 99. MacKay, 1931, p. 187. Clemens, 1933, p. 51. Imaizumi, 

 1952, p. 181. 



