406 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.21 



Types: Two females, cotypes, originally deposited in the Museum 

 of the Zoological Society [London] and the Bell Museum, no longer 

 extant. Length of measured cotype 25.4 mm, width 12.7 mm. 



Type locality: Galapagos Islands, 6 fathoms; Hugh Cuming, col- 

 lector. 



Localities subsequently reported, with collectors: Lower California, 

 Mexico: off Abreojos Point, 48 fathoms, Albatross (Rathbun, 1898, as 

 Stenocionops triangulatd) ; Magdalena Bay, 13.5 fathoms, Albatross 

 (Rathbun, 1923b, as S. triangulata) ; off Redondo Point, 47 fathoms, 

 Albatross (Rathbun, 1925, as S. triangulata) ; Gulf of California, 

 Mexico: off Cape Lobos, 76 fathoms, northwest of Tiburon Island, 145 

 fathoms, and northwest of Guaymas, 71 fathoms, type locality of S. mac- 

 donaldi, Albatross (Rathbun, 1892, as Libinia macdonaldi) ; southwest 

 of Tiburon Island, 29 fathoms, Albatross, type locality of Stenocionops 

 triangulata, and inside San Jose Island, 33 fathoms, Albatross (Rath- 

 bun, 1892, as Pericera triangulata) ; Arena Bank, 45-55 fathoms, Zaca 

 (Crane, as Stenocionops macdonaldi). 



Panama: Banco Hannibal, Isla Coiba, 40 fathoms, Alva (Boone, 

 1938) ; Bay of Panama, 51.5 fathoms, Albatross (Rathbun, 1898, as 

 Stenocionops triangulata), 33 fathoms, Albatross (Rathbun, 1925, a« 

 S. macdonaldi). 



Ecuador: Galapagos Islands: Wenman, Chatham, Indefatigable, 

 Albemarle, and Hood Islands, 12-150 fathoms, Velero HI (Garth, 1946, 

 as Stenocionops triangulata) . 



Atlantic analogue: Stenocionops spinimana (Rathbun). 



Diagnosis: Adult: Rostral horns short, from one-seventh to one- 

 twelfth carapace length. Five lateral marginal spines, two hepatic, three 

 branchial, the latter often with accessory spinules. Nine median dorsal 

 spines. Tip of male first pleopod convoluted, opening concealed beneath 

 fold ; triangular keel little advanced but greatly broadened. 



Description: Adult: [Carapace rotund and spinous,] hepatic region 

 separately prominent, the after part of the carapace subspherical. Hairy 

 covering a very thick and dense pile. Spines conical, blunt or subacute. 

 Median spines nine : four gastric, one genital, two cardiac, two intestinal, 

 none on posterior margin. Of the lateral spines, two hepatic (exception- 

 ally an additional spinule), the anterior the smaller; three anterolateral 

 branchial spines, the middle one the largest ; and two above the postero- 

 lateral margin, the last one the smaller and sometimes absent. From the 

 first of these a row of six low spines extending to the middle of the 

 hepatic region. Another small hepatic spine nearer the margins, some- 



