ASTEROIDEA ,97 



examples (e.g. R 13 mm.) have usually 5 ambulacral and 5 oral spines and the same 

 number of paxillar spines as the adult. 



It is probable that these specimens are not typical brachiatiis, but are near to that race 

 and emphasize its close similarity to lebruni. Koehler states that the paxillae of his type 

 "ne comprennent guere qu'une demi-douzaine de piquants divergents, dont I'un, plus 

 developpe, souleve la tente dorsale et la perce pour faire saillie au dehors". " Scarcely 

 half a dozen " is not greatly different from 3 to 5, while the puncturing of the supradorsal 

 membrane is not a normal condition, but an accident either of handling or preservation. 



One stomach contained some remains of branching bryozoans and miscellaneous 

 organic debris. 



Type locality. Kerguelen. 



Subgenus Retaster 

 Pteraster gibber (Sladen) 



Retaster gibber Sladen, 1889, p. 4S1, pi. 74, figs. 5 and 6; pi. 77, figs. 7 and 8. — Ludwig, 1905, p. 65, 



pi. 6, figs. 6 and 7. — Bernasconi, 1937, p. 185. 



St. WS 248. Falkland Islands, 52° 40' S, 58° 30' W, 210-242 m., fine green sand, pebbles, shells, 

 I specimen. 



The specimen is smaller than Sladen 's type, with broader rays, so that the contour is 

 subpentagonal. R 20 mm., r 12 mm.ib, R=i'6 r. The abactinal surface is arched, the 

 body being thick and cushion-like. The supradorsal membrane shows the characteristic 

 quadrate and pentagonal reticulum figured by Sladen. The actinolateral membrane is 

 very narrow. The adambulacral combs contain 6 spines instead of the 5 figured by 

 Sladen. The innermost or furrow spinelet is small and the fan here curves distad. Each 

 oral plate carries a marginal series of 8 spines (the outermost 4 being small). The 16 are 

 united in a single web. Sladen states that the type carries 3 oral spines per plate. This is 

 a big discrepancy even for variable Pteraster. It seems likely that the outer spinelets 

 were overlooked, as Ludwig (1905, p. 66) has indicated. Ludwig's larger specimen 

 carried 6 oral spines (R 18 mm.). 



The largest paxillae, supporting the interradial lateral portion of the supradorsal 

 membrane, consist of an elongate pedicel and 7-9 peripheral spinelets meeting the 

 supradorsal membrane on the periphery of the areoles. There is a central group of 3 or 4 

 spinelets, slenderer and more acute than the peripheral, the tips of which are usually 

 slightly clavate and thorny. 



Pt. gibber is closely related to Pt. tesselatus Ives^ and Pt. capensis (Perrier).^ The first 

 ranges from Bering Sea to Washington ; the second is from the Cape region of Africa. 



Clark remarks on the close resemblance of Pt. capevsis and Pt. tesselatus, stating that 

 the only constant difference between the two species " seems to be in the structure of the 

 paxilla : in capensis each paxilla has a single central spinelet of a size about equal to the 

 surrounding series of 6 or 7 similar spinelets, while in tesselatus instead of this central 



1 Fisher, 191 1, p. 359, pi. 104, figs. 1-5. 



^ Clark, 1923, p. 299, pi. 9, figs. 3 and 4. Mortensen, 1933, p. 267, pi. 14, figs. 1-3; text-fig. 9. 



D X.X 17 



