KEPORT ON THE ASTEROID EA. 167 



111 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" S., 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 

 cribriform 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. 

 Tlwracaster, Sladen, Journ. Linn. Soc. Lond. (Zool.), 1S83, 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 paxillae. 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. 



Ambulacra! 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 arc, in the single species 

 known. 



Terminal plate small, inconspicuous, and unarmed. 



