REPORT ON THE ASTEROIDEA. 167 
In the neighbourhood of the mouth-angle, and adjoining the adambulacral plates, the 
actinal intermediate plates become larger and altered in form, and appear independent 
of the series of columns. The actinal interradial area is covered with a very fine and 
almost imperceptible membrane, plates and membrane together being so thin that traces 
of the internal organs of the starfish can be seen through them. A number of small 
irregularly disposed granules are distributed over the area, but seldom more than two 
or three are present on a plate, and they are often wanting. The imbrication of the 
plates appears to be very slight in this species, and is perhaps only present in the outer 
part of the areas. 
Colour in alcohol, grey, with traces of a purple shade remaining here and there upon 
the paxillar area and on the rays. 
Locality.—Station 157. In the Southern Ocean, near the meridian of 110° E. 
March 3, 1874. lat. 53° 55’ 0” &., long. 108° 35’ 0” E. Depth 1950 fathoms. 
Diatom ooze. Bottom temperature 32°°1 Fahr. ; surface temperature 37°°2 Fahr. 
Remarks.—This species is at once distinguished from the other species with seven 
eribriform organs by the supero-marginal plates of the two sides of a ray not meeting 
in the median radial line, but in being separated by a band of membrane; and also 
by the presence of the secondary or actinal series of granules behind the furrow series 
on the surface of the adambulacral plates. 
Genus Thoracaster, Sladen. 
Thoracaster, Sladen, Journ, Linn, Soc. Lond. (Zool.), 1883, vol. xvii. p. 245. 
Rays five, moderately long, cylindrical, and rigid. Disk large, and capable of slight 
inflation, 
Supero-marginal plates united in the median radial line, forming a cylindrical encase- 
ment to the ray. Marginal plates devoid of spinelets. 
Abactinal area covered with small closely crowded paxille. No central epiproctal 
protuberance present. 
Actinal interradial areas extensive, paved with plates imbedded in membrane, and 
carrying numerous small, uniform, rather closely placed, papilliform granules or spinelets. 
Ambulacral furrows narrow and enclosed. Armature of the adambulacral plates, con- 
sisting of short equal spines, ranged on the furrow margin of the plate, and forming a 
lineal series along the ray. The actinal surface or outer portion of the plate is occupied 
by small papilliform spinelets more or less definitely arranged. 
Cribriform organs fourteen in number in each interbrachial are, in the single species 
known, 
Terminal plate small, inconspicuous, and unarmed. 
