REPORT ON THE ASTEROIDEA. 335 
about seventy-five adambulacral plates may be counted along the furrow. Their arma- 
ture consists of delicate tapering spines, irregular in number and disposition, forming a 
compact group, which occupies the whole surface of the plate, transversely elongate in form 
in relation to the direction of the ray, and resembles a compressed and enlarged paxilla. 
There are fifteen to twenty spinelets in each group. Two of the spinelets (sometimes 
three) larger than the rest, slightly flattened, and tapering to a point, stand at the margin 
of the furrow, their relative position being generally slightly oblique. The succeeding 
spinelets are less robust, and pass in gradation to the group of outermost spinelets, which 
are about equal in size to the paxille of the actinal intermediate plates. The five or six 
innermost adambulacral plates have much larger spinelets than the others. 
The united mouth-plates form a sharp angle inwardly, and a large elongately ovoid, 
subtubercular swelling is developed on their superficies,—the whole surface being covered 
with spinelets arranged in somewhat similar series to the spinelets of the adambulacral 
armature, standing perpendicular, seven to eight along each side of the mouth-angle. The 
aboral portion of each plate is occupied by a compressed paxilliform group similar to those 
of the adambulacral plates. 
The madreporiform body is obscure and concealed by paxille. 
The ambulacral tube-feet, which are arranged in pairs, are robust and large, with a well- 
developed fleshy disk, devoid of spicules. 
No traces of any form of pedicellarize are present. 
Colour in aleohol, a dirty yellowish ashy grey, or with a light brownish shade. 
Localities—“‘ Knight Errant ” Expedition : 
Station 4. In the Faerée Channel. August 10,1880. Lat. 59° 33’ 0” N., long. 7° 
14/0” W. Depth 555 fathoms, Mud. Bottom temperature 45°-4 Fahr. ; surface tem- 
perature 57°°0 Fahr. 
“Triton ” Expedition : 
Station 10. In the Faerée Channel. August 24,1882. Lat. 59° 40’ 0” N., long. 
7° 21'0” W. Depth 516 fathoms. Bottom temperature 46°°0 Fahr. 
Station 11. In the Faerde Channel. August 28,1882. Lat. 59° 29’ 0” N., long. 
7°13’ 0” W. Depth 555 fathoms. Bottom temperature 45°°5 Fahr. 
Remarks.—The arrangement and appearance of the paxillee, and the numerous papulz 
interspersed, recall in a striking manner the habit of Solaster. On dissection, however, 
it is found that this’ appearance is deceptive and not real, and that the true structural 
resemblance lies in a very different and unexpected direction. In Solaster endeca, the 
form which at first sight is most nearly suggested by the dorsal covering of this species, 
the abactinal portion of the skeleton consists of a rather closely reticulated calcareous 
framework, built up of small imbricating plates, upon certain of which the paxillee are 
borne. The skeleton of Mimaster, on the other hand, is constructed quite differently, 
the whole abactinal floor being composed of paxille alone, each of the paxillze consisting 
