466 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 5 



Material examined. — 



58-33. Cormorant Bay, Charles Island, not over 13 fms, Feb. 6, 1933, 

 1 young female (photographed). 



Aleasurernents. — Female: length 6.3 mm, width 7.8 mm, cheliped 

 9.5 mm, chela 5.0 mm, dactyl 3.0 mm. 



Depth. — The Galapagos specimen was dredged in not over 13 fms. 



Remarks. — The sending of this unique specimen in Hancock collec- 

 tions to Dr. Fenner A. Chace for comparison with the type of Xanthodes 

 bidentatus A. Milne Edwards resulted in a complete review of the 

 Atlantic species of Tetraxanthus by Dr. Chace, involving the suppression 

 of T. rugosus Rathbun (1930) and the establishment of T. bidentatus 

 Rathbun (1898) as T. rathbunae Chace with recent Atlantis material 

 for types. 



The Galapagos specimen, though differing in minor particulars, is 

 tentatively referred to the latter species until more material is available 

 on which to base a Pacific species of Tetraxanthus. 



Genus EGTAESTHESIUS Rathbun, 1898 



Ectaesthesius bifrons Rathbun 



Plate 58, Figs. 1-7 



Ectaesthesius bifrons Rathbun, Proc. U.S. Nat. Mus., vol. 21, p. 591, pi. 

 42, figs. 12-14, 1898; Bull. 152, U.S. Nat. Mus., p. 460, text fig. 

 76a-c, 1930. 

 Type locality. — Off Chatham Island, Galapagos Islands ; 45 fms. 

 Type.—\]?>NM No. 21586. 

 Range. — Known only from the type locality. 



Diagnosis. — Carapace smooth and glabrous, anterior margins biden- 

 tate, posterior margins strongly converging. Orbits completely closed. 

 Fingers long and tapering. Legs with last three segments hairy; dactyls 

 as long as propodi. 



Material examined (9 specimens from 4 stations). — 

 346-35. South Seymour Island, 55 fms, Dec. 13, 1934, 1 male. 

 795-38. Sulivan Bay, James Island, 35-40 fms, Jan. 21, 1938, 2 males 

 (1 illustrated), 1 female (illustrated in part), 2 young. 

 795a-38. Sulivan Bay, James Island, 50-60 fms, Jan. 21, 1938, 1 female, 

 1 young. 

 814-38. North of Hood Island, 20-40 fms, Jan. 28, 1938, 1 female. 

 Measurements. — Largest male: length 9.3 mm, width 12.9 mm, 

 cheliped 19.0 mm, chela 11. 8 mm, dactyl 6.4 mm ; female : length 8.2 mm, 

 width 11.4 mm. 



Habitat. — Sand and rock, sand and shell, mud and shell. 

 Depth.— 20-60 fms. 



