REPORT ON THE ASTEROIDEA. 407 
half of its margin are more papilliform than the other granules on the abactinal plates 
generally. 
The anal aperture is small and excentric in position, and is surrounded by a number 
of small scutiform papillae, which trend over the orifice. 
The primary apical plates are very conspicuous. 
Colour in alcohol, a brownish white, mottled with patches on the abactinal area of a 
light chocolate colour. All the papular areas are a dark greyish brown. This distribution 
of colour produces a very ornate appearance. ‘The actinal surface is yellowish white. 
Locality.—Station 187. Booby Island, Torres Strait. September 9,1874. Lat. 10° 
36’ 0” §., long. 141° 55’ 0” KE. Depth 6 fathoms. Coral mud. Surface temperature 
77°°¢ Eahr. 
Remarks.—This large and elegant form is distinct from any other species with which 
I am acquainted. It resembles in some of its details Ophidiaster tuberifer, but is readily 
distinguished by the larger size, the tapering rays, the absence of tubercles on the 
abactinal plates, the small size of the granulation on the abactinal plates, the peculiar 
character and disposition of the granulation of the papular areas, the difference in the 
adambulacral armature (which in Ophidiaster helicostichus is in two series, whereas in 
Ophidiaster tuberifer three series are present), and in the presence of the large-bossed 
pedicellariz. The pedicellariz generally are, if anything, smaller in the species under 
notice than in Ophidiaster tuberifer. 
Genus Leiaster, Peters. 
Leiaster (subgen.), Peters, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, April 1852, p. 177. 
Lepidaster, Verrill, Trans. Conn, Acad. Arts and Sci., 1871, vol. i. part 2, p. 577 (non Lepidaster, Forbes, 
1850). 
Ophidiaster (pars), Perrier, Révis. Stell. Mus., p. 121 (Archives de Zool. expér., 1875, t. iv. p. 385). 
This small group of species, although distinctly allied to Ophidiaster, appears to me 
worthy of generic recognition. The soft thick skin with which they are covered causes 
them to have a gelatinous or slimy character to the touch when alive, and this together 
with minor differences of structure produces a facies altogether different from that 
of any of the species of true Ophidiaster. Von Martens’ and de Loriol® have both 
expressed the same opinion. Lezaster, as at present known, is confined to the Indian Ocean, 
the Eastern Archipelago, and the Pacific, and appears to be local in its occurrences. 
Chorology of the Genus Leiaster. 
a. Geographical distribution :— 
Inp1an Ocean: Three species between the parallels of 10° and 30° S. 
Levaster coriaceus and Leiaster glaber, from Querimba Island. 
Leiaster coriaceus and Leiaster leachii, from Mauritius. 
1 Archiv f. Naturgesch., Jahrg. xxxii., Bd. i. p. 71. 
2 Mém. Soc. phys. hist. nat. Genéve, t. xxix. p. 40. 
