REPORT ON THE ASTEROIDEA, 99 
spines. ‘The spines are short, increasing slightly as they approach the mouth, the outer- 
most being much smaller than any of the others. They are slightly subclavate and 
slightly curved, and radiating apart form an elegant armature. The actinal surface of the 
plate is covered with numerous short, obtuse, papilliform spinelets, which increase in 
leneth and robustness as they proceed towards the inner end of the mouth-plates, those 
next the marginal series being nearly equal to them in length and very much more robust. 
The actinal interradial areas are large and well-developed, and occupied by plates 
arranged in regular series or columns passing from the adambulacral plates to the marginal 
plates. Five or six plates may be counted in the series on each side of the median inter- 
radial line, and each of the plates in the column imbricates slightly on the next outward 
plate. Naturally the number of plates in a column decreases as the columns proceed 
along the ray, and no intermediate plates extend beyond the ninth or tenth adambulacral 
plate. The intermediate plates adjacent to the adambulacral plates are equal in breadth 
to the length of the adambulacral plates, and the succeeding plates in a column diminish 
slightly as they proceed outward. The surface of the intermediate plates is covered with 
short, uniform, papilliform granules, which form regular rectangular groups, each group 
being marked out by distinct and well-defined suture-lines or channels from those adjacent, 
the recularity of the arrangement of the plates being very conspicuous. 
The anal aperture is subcentral, but often inconspicuous, as there is nothing in the 
character of the paxillze in its neighbourhood to indicate its presence. 
The madreporiform body is obscure and hidden by paxille, a group of two or three in 
that position being rather larger than any of the others on the abactinal surface. The 
position is about one-third of the distance from the margin to the centre. 
The ambulacral tube-feet are large and conical, with a small mamelon-like subconical 
termination. 
Colour in alcohol, a greyish white, with a slightly darker or ashy shade over the 
paxillar area. 
Locality.—Station 73. West of Fayal, Azores. June 30, 1873. Lat. 38° 30’ 0” N., 
long. 31° 14’ 0” W. Depth 1000 fathoms. Pteropod ooze. Bottom temperature 39°°4 
Fahr. ; surface temperature 69°°0 Fahr. 
Remarks.—Plutonaster notatus is most nearly allied to Plutonaster abbreviatus, but 
is distinguished by the broad disk and very narrow rays. These characters also serve 
to separate it at a glance from the other species; and it is further distinguished by the 
absence of any spines either on the superior or inferior series of marginal plates. In 
the largest example in the collection, however, minute or rudimentary representatives of 
infero-marginal spinelets are present on the plates in the interbrachial are. 
6. Plutonaster abbreviatus, n. sp. 
Rays five R=20mm.; r=7'5mm. R>25r. Breadth of aray between the third 
and fourth supero-marginal plates, 5 mm. 
