366 THE VOYAGE OF H.M.S. CHALLENGER. 
spinelet, the membrane mounting the base and causing it to appear very robust and broad. 
There is thus a series of spinelets running parallel to the margin. One or two plates on 
the inner part of the area bear a similar spine, but only one appears to be regular in 
occurrence, and that is situated near the apex of the area. 
The abactinal area is covered with thick membrane, and although the individual plates 
are indistinguishable, many of them appear to be comparatively large. They bear groups 
of small, equal, robust, papilliform granules, scarcely worthy of being called spines; and 
these groups have an isolated appearance. Comparatively large, isolated, single papule, 
widely spaced, are distributed over the surface, excepting a narrow area along the median 
radial and the median interradial lines; along the outer part of the latter is a faint 
channel. 
The madreporiform body, which is small and circular, is situated about midway 
between the centre of the disk and the margin. 
The anal aperture, which is large and conspicuous, is margined by small papilliform 
spines. 
Colour in alcohol, bleached yellow, with a light brown shade in places. 
Locality. —* Porcupine” Expedition : 
Station 31. Between the north of Ireland and Rockall. Lat. 56° 15’ N., long. 11° 25’ 
W. Depth 1360 fathoms. Bottom temperature 2°°9 C.; surface temperature 13°°8 C. 
Remarks.—So far as I can judge from the short descriptions of the three’ species 
hitherto known, together with the figures of two of them, this form appears to me unques- 
tionably different from any of them. 
Marginaster fimbriatus differs from Marginaster pectinatus, Perrier, in having groups 
of granules on the abactinal plates; and in the absence of the comb of spinelets on the 
supero-marginal plates, which according to Perrier’s description are present in Marginaster 
pectinatus, and similar to those on the infero-marginal plates. The armature of the 
adambulacral plates is also different, and the lineal series of spinelets on the actinal inter- 
radial areas parallel to the margin are wanting in Marginaster pectinatus. 
Marginaster pentagonus, Perrier, differs in having the abactinal plates furnished with 
spines disposed in irregular ares on the margin of the plates; in the large number of 
spines which form the comb on the marginal plates (about ten); and in the armature of 
the adambulacral plates. 
Marginaster echinulatus, Perrier, differs in the stellate form; in the totally different 
character of the adambulacral armature; in the presence of two spines on each actinal 
intermediate plate; in having only a single row of papulze on each side of the median 
radial line ; and in the peculiar form of the plates which occupy the median radial line (as 
shown in the figure). 
1 Perhaps the starfish described by Gasco (Rendic. R. Acead. Sci. Fis. e. Mat. Napoli, 1876, Anno xv., 
fasc. 2, p. 9), under the name of Asferopsis capreensis, may ultimately prove to belong to this genus also. 
