594 THE VOYAGE OF H.M.S. CHALLENGER. | 
b. No papule 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 papule. 
a. No azygos interradial plate separating the first pair of adambulacral 
plates . ae ple ° . ° . : . Freyella. 
b. An azygos interradial plate separating the first pair of adambulacral 
plates “ 2 * “ ; ° . 2 5 5 5 Colpaster. 
Genus Labidiaster, Liitken. 
Labidiaster, Liitken, Videnskab. Medd, naturh. Foren. i Kjgbenhavn, 1871, p. 289. 
The genus Labidiaster was considered by Liitken as most nearly allied to Pedicellaster. 
It was placed by Perrier* in 1878 in the family Asteriidze, but was subsequently ranked 
by Viguier’ along with Brisinga and Pedicellaster in the family Brisingide. The recent 
researches of Studer*® 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,* be a distinct 
species, for which, if necessary, he proposes the name Labidiaster 
luetkent.) — 
SouTHERN OcEan: One species between the parallels of 45° and 55° 8. 
Labidiaster annulatus, off Kerguelen Island and Heard Island, 
and extending into the Arafura Sea. 
EastERN ARCHIPELAGO: One species between the parallels of 0° and 10° 8. 
Labidiaster annulatus, from north-west of the Arrou Islands, 
1 Nouv. Archives Mus. Hist. Nat., 2c Série, 1878, t. i. pp. 10, 44, 76. 
* Archives de Zool. expér., 1878, t. vii. Doe 
* Anhang zd. Abhandl. d. k. preuss. Akad. d. Wiss. Berlin, yom Jahre 1884, p. 14. 
* Proc. Zool. Soc. Lond., 1881, p. 94. 
