224 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.21 



Type locality: The Antilles. "Guadeloupe" on the typa specimen. 



Pacific localities subsequently reported, with collectors: Mexico: 

 Lower California: Magdalena Bay (Rathbun, 1925) ; Cape San Lucas, 

 John Xantus (Stimpson) ; Manzanillo, F. Bonet (Buitendijk). Nica- 

 ragua: Corinto, Zaca (Crane). Costa Rica: Piedra Blanca, Zaca 

 (Crane). Panama: Bay of Panama, Vettor Pisani (Cano) ; Perico 

 Island, Albatross (Rathbun, 1907). Ecuador: Galapagos Islands, 5 

 fathoms, Hugh Cuming (Bell) ; St. George (Finnegan) ; Hood Island, 

 15 feet, Arcturus (Boone) ; Academy Bay, Rolf Blomberg (Hult) ; 

 Hood, Charles, Barrington, Albemarle, and Indefatigable Islands, Velero 

 III (Garth). Peru: "Peru" (Miers, 1877) : Sechura Bay, 5-6 fathoms, 

 R. E. Coker (Rathbun, 1910) ; near Lima (Milne Edwards and Lucas, 

 as Acanthonyx emarginatus) ; Callao, Vettor Pisani (Cano) ; North 

 Chinchas Island, 7-10 fathoms (Kinahan, as Acanthonyx concamerata) , 

 R. E. Coker (Rathbun, 1910), R. C. Murphy (Rathbun, 1925); 

 Paracas Bay, Hassler (Rathbun, 1925). Chile: Caldera, Hassler (Rath- 

 bun, 1925) ; Valparaiso, U. S. Exploring Expedition (Dana, 1851a, as 

 Acanthonyx debilis), Vettor Pisani (Cano). 



Atlantic analogue: The species itself is considered common to both 

 sides of the Isthmus of Panama, no satisfactory basis having been found 

 for separating the Pacific from the Atlantic form. 



Diagnosis: Rostrum short, deflexed, bifid. An elevated preorbital 

 lobe. Hepatic lobe large, rectangular; two setose branchial lobes or 

 teeth. Carapace nearly smooth; five obscure setiferous tubercles: three 

 gastric, one cardiac, one intestinal. Carpus of male cheliped crested, 

 manus enlarged and compressed, fingers denticulate. Ambulatory legs 

 subchelate. Abdomen six-segmented in both sexes ; male first pleopod 

 with a thickened tip opposed by a triangular, spinulous lobe. 



Description: Carapace elongate, subpentagonal, nearly smooth, a few 

 tufts of hair; lateral margins nearly parallel, tridentate, first tooth large, 

 at anterolateral angle; preorbital tooth present; rostrum short, deflexed, 

 tip bifurcate; each marginal tooth fringed with hair. Antennae visible 

 either side of beak. Orbits in sides of carapace; eyes visible from above. 

 Chelipeds short, considerably enlarged in male; two tubercles on lower 

 outer edge of arm ; wrist cristate above ; palm longer than narrowly 

 gaping fingers. Legs compressed, decreasing in length from first to 

 fourth; propodi dilated, a blunt tooth on under edge against which the 

 dactylus plays. (Rathbun, 1910) 



According to Rathbun (1925, p. 143), different names have been 

 given to this species on the basis of the size of the male cheliped, the 



