594 THE VOYAGE OF H.M.S. CHALLENGER. 



b. No papula? in the intermediate abactinal membrane .... Brisinga. 

 b. Abactinal plating of the disk and basal portion of the rays consisting of 

 scale-like imbricating plates. No papula;. 



a. No azygos interradial plate separating the first pair of adambulacral 



plates Freyella. 



b. An azygos interradial plate separating the first pair of adambulacral 



plates Colpaster. 



Genus Labidiaster, Liitken. 



Labidiaster, Liitken, Videnskab. Medd. naturh. Foren. i Ej0benhavn, 1871, p. 289. 



The genus Labidiaster was considered by Liitken as most nearly allied to Pcdicellaster. 

 It was placed by Perrier 1 in 1878 in the family Asteriidse, but was subsequently ranked 

 by Viguier 2 along with Brisinga and Pediccllaster in the family Brisingidse. The recent 

 researches of Studer 3 have fully confirmed the justice of placing Labidiaster in that 

 family. Hitherto the genus was supposed to be confined to the southern point of the 

 American continent ; its range is now, however, considerably extended by its discovery 

 in the Southern Ocean and in the Arafura Sea. The occurrence of this and other 

 Antarctic species in the last-mentioned region is highly remarkable, and would have 

 been almost suggestive of an error in labelling if one case only had occurred. 



Chorology of the Genus Labidiaster. 

 a. Geographical distribution : — 



Atlantic : One species between the parallels of 30° and 55° S. 



Labidiaster radiosus, off the eastern coast of Patagonia, passing 

 as far north as the mouth of the Rio de la Plata (fide Kinberg), also 

 in the Strait of Magellan, and extending to the Pacific side in the 

 Trinidad Channel. (This may, perhaps, fide Bell, 4 be a distinct 

 species, for which, if necessary, he proposes the name Labidiaster 

 luetkeni.) 



Southern Ocean : One species between the parallels of 45° and 55° S. 



Labidiaster anmdatus, off Kerguelen Island and Heard Island, 

 and extending into the Arafura Sea. 

 Eastern Archipelago : One species between the parallels of 0° and 10° S. 



Labidiaster annulatus, from north-west of the Arrou Islands, 



1 Nouv. Archives Mus. Hist. Nat, 2e Sene, 1878, t. i. pp. 10, 44, 76. 



2 Archives de Zool. exper., 1878, t. vii. p. 119. 



3 Anhang z. d. Abhandl. d. lc. preuss. Akad. d. Wiss. Berlin, vom Jahre 1884, p. 14. 



4 Proc. Zool. Soc. Lond,, 1881, p. 94. 



