192 THE VOYAGE OF H.M.S. CHALLENGER.’ 
Colour in alcohol, a dirty ashy or brownish grey. 
Locality.—Station 148. Between Marion Island and Kerguelen Island. January 38, 
1874. Lat. 46° 47'0”S., long. 51° 37/0” E. Depth 210 fathoms. Hard ground (gravel, 
shells). Surface temperature 41°°0 Fahr. 
Remarks.—This form is unquestionably the southern representative of Leptopty- 
chaster arcticus, Sars, sp. of the North Atlantic, to which it is structurally nearly 
related. It is distinguished by the comparatively larger disk and shorter rays, the latter 
being also broader at the base and more sharply pointed at the extremity. The supero- 
marginal plates are relatively smaller or more aborted, the paxille of the abactinal area 
are smaller and less compact, and the adambulacral armature is usually more compact 
and grouped in its disposition. Leptoptychaster kerguelenensis, Smith, is distinguished 
by the longer and more cylindrically rounded rays, by the larger and more compact 
paxille of the abactinal surface, by the smaller actinal interradial areas, and, above all, 
by the characteristic adambulacral armature, almost recalling that of Cribredla in its 
character. 
It is interesting to note that Leptoptychaster antarcticus is more nearly related to 
the distant Arctic form than to the comparatively neighbouring species Leptoptychaster 
kerguelenensis ; perhaps a more extended series of specimens than we possess at present 
might lead to Leptoptychaster antarcticus being ranked as a variety only of the northern 
form. At present I do not feel justified in taking that step. 
Genus Movraster, n. gen. 
Disk large. Rays rather elongate, broad at the base and tapering to the extremity. 
Marginal plates of both series with well-developed ridges, separated by deep fasciolar 
channels. Infero-marginal plates with large flattened spatulate spinelets, chisel-shaped or 
square-cut at the tip. No prominent large spines on either series. 
Abactinal area with paxille borne on stellate plates, without internal imbricating 
ridges. Paxillae with long pedicles, and erect compact crowns of short inbending spinelets. 
No definite medio-radial series. 
Actinal interradial areas large, with numerous intermediate plates arranged in regular 
transverse columns, each plate imbricating on its neighbour in its own column. The 
intermediate plates extend along fully two-thirds of the ray, and all bear stout, flattened, 
spatulate spinelets. 
Armature of the adambulacral plates more or less regularly triserial, simulating that 
of Astropecten. A series of usually three spines form a triangle on the furrow margin, 
and are followed by two outer series of two or three stout chisel-shaped spines, similar to 
those on the actinal intermediate plates. 
Strongly developed superambulacral plates are present. 
