PART 1 GARTH : PACIFIC OXYRHYNCHA 147 



vak Island, Canadian Arctic Expedition (Rathbun, 1919). Alaska, W. 

 J. Fisher (Lockington) ; Shumagin Islands, Alaska Peninsula, Canadian 

 Arctic Expedition (Rathbun, 1919). 



Atlantic analogue: The subspecies Hyas coarctatus alutaceus is 

 found off Labrador, Newfoundland, and Cape Breton Island. Elsewhere 

 in the North Atlantic typical H. coarctatus occurs. 



Diagnosis: Rostral horns short and broad. Exorbital tooth and 

 hepatic lobe presenting a continuous convex surface. Branchial row of 

 tubercles poorly defined. Basal antennal article with a small blunt tooth 

 at anteroexternal angle. Cheliped of adult male short, hand broad. Male 

 first pleopod with tip slender, inclined, a short row of 5 filaments on 

 one side and a long row of 12 filaments, 7 of them backed by another 

 row, on opposite sides of a line projected basally from the subterminal 

 aperture. 



Description: Deviates from typical Hyas coarctatus through the 

 somewhat more strongly roughened ("chagrinirte") dorsal surface of the 

 cephalothorax, through a somewhat broader posterior part of the body, 

 and through somewhat broader chelae, so that through its body form it 

 approaches somewhat more Hyas araneus, particularly younger examples 

 of the latter. (Brandt) 



The body is thicker and much broader anteriorly across the postor- 

 bital apophyses than [Hyas coarctatus] ; the angles are all more obtuse. 

 The dorsal surface is marked with fewer tubercles, which are also much 

 larger and more obtuse, most of them being rather swellings than warts. 

 The rostrum is shorter and less acute; and the superior fissure of the 

 orbit is always closed, its margins overlapping. (Stimpson, 1907, of H. 

 latifrons, a synonym of H. c. alutaceus) 



Material examined: Between Pribilof Islands and Bristol Bay, 

 Bering Sea, 25.5 fathoms, June 14, 1890, Albatross station 3251, 1 male, 

 1 female, identified by J. E. Benedict (U.S.N.M. No. 15873, part). 

 Also 26 specimens from nine Arctic Ocean localities, all off Point Bar- 

 row, G. E. MacGinitie, collector. (See Table 25) 



Measurements: Bering Sea male: length 46.8 mm, branchial width 

 36.6 mm, hepatic width 28.7 mm, rostrum 4.5 mm, width 7.0 mm, 

 cheliped 52 mm, chela 23.6 mm, dactyl 13.0 mm, height of palm 8.7 mm, 

 ambulatory legs 67, 62, 58, and 55 mm, respectively. Ovigerous female: 

 length 51.0 mm, branchial width 40.0 mm, hepatic width 30.5 mm, 

 cheliped 49 mm. Arctic Ocean male: length 73 mm, branchial width 58 

 mm, hepatic width 43 mm, rostrum 6.4 mm, width 9.5 mm, cheliped 

 137 mm, chela 60 mm, dactyl 31 mm, height of palm 20 mm, am- 

 bulatory legs 137, 120 (125), 118, and 113 mm, respectively. 



