ASTEROIDEA 191 



transverse series of 4-6, spaced and sheathed separately in membrane. Mouth-plates 

 fairly large, of the type of the Pterasteridae, and with a prominent median keel ; a few 

 marginal spines and a single or no suboral spine. Membranous interradial septum; 

 gonads opening dorsally ; tube-feet in 2 or 4 rows with fleshy, button-like terminal disk, 

 devoid of deposits. No pedicellariae. 



Type locality of P. folliculatus. Challenger St. 304, off the Peninsula of Tres 

 Montes, Chile, 46° 53' 15" S, 75° 12' W, 45 fathoms, green mud. 



Distribution. Southern Chile, the Falkland Plateau, and off Marion Island, 81- 



Peribolaster macleani Koehler 



Peribolaster MacLeani Koehler, 1920, p. 161, pi. 31, figs. 2, 5; pi. 33, figs, i and 2; pi. 68, fig. 4. 

 St. 1660. Ross Sea, 74° 46-4' S, 178° 23-4' E, 351 m., i specimen. 



The type specimen measured R 24 mm., r 9-5 mm., whereas the Discovery specimen 

 has R 9 mm., r 3 mm. As Koehler has indicated the species is nearer to P. biserialis 

 Fisher of the north Pacific than to P. folliculatus. But the subambulacral and marginal 

 spines are entirely different to those of biserialis, being more or less flattened, broader at 

 tip than near base, and terminated by several unequal, sharp awns (Koehler, pi. 68, 

 fig. 4, b, c). 



Type locality. 66° 32' S, 141° 39' E, 151 fathoms. 



Distribution. Antarctica (Australian Quadrant) from Queen Mary Land east to 

 Ross Sea (longitude 94°-i78°E) never far north of summer ice (latitude 64^32'- 

 74° 46-4'); 191-581 m. 



Family PTERASTERIDAE Perrier, 1875 

 Genus Pteraster Miiller & Troschel 



Pteraster Miiller & Troschel, 1842, p. 128.— Type Asterias militaris O. F. Muller (monotypic). 

 Retaster Perrier, Nouv. Arch. Mus. Hist. Nat., 2^ ser., i, 1878, p. 56.— Type Pteraster capensis Gray, 



by designation, Fisher, 1919, p. 460. 

 Hexaster Perrier, Comptes rendus, cxn, no. 21, i May 1891, p. 1227; Mem. soc. zool. France, iv, 1891, 



p. 267. Type Hexaster obscurus (monotypic). 

 Temnaster Verrill (subgenus), Proc. U.S. Nat. Mus., xvii, 1894, p. 275; Ainer. J. Sci., XLix, 1905, 



p. 202 (as genus). Type Pteraster {Temnaster) hexactis = Pteraster obscurus (Perrier). 

 Lophopteraster Verrill, Amer. J. Sci., XLix, 1895, p. 202. Type Pteraster abyssorum Verrill. 

 Pterasterides Verrill, Amer. Naturalist, XLiii, 1909, p. 547, footnote. Type Pteraster aporus Ludwig = 



Pteraster militaris (O. F. M.). 



The genus Pteraster has now accumulated a considerable number of nominal species. 

 Within this assemblage there appears to be at least three natural groups, or sections. 

 These are hardly of generic importance, but as subgenera will be of distinct service. By 

 allocating a new species to its particular group, the task of identification is simplified at 

 the outset. Subgenera can also lessen the danger of contrasting a new form with irrele- 

 vant species, on the ground of geographical proximity. The literature of every large 



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