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 paxillse 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 paxillse. 



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 pedicellarise are present. 



Colour in alcohol, a dirty yellowish ashy grey, or with a light brownish shade. 



Localities. — " Knight Errant " Expedition : 



Station 4. In the Faeroe 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 Faeroe Channel. August 24, 1882. Lat. 59° 40' 0" N., long. 

 7° 21' 0" W. Depth 516 fathoms. Bottom temperature 46 o, Fahr. 



Station 11. In the Faeroe 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 paxillse, and the numerous papulae 

 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 paxillse are 

 borne. The skeleton of Mimaster, on the other hand, is constructed quite differently, 

 the whole abactinal floor being composed of paxillse alone, each of the paxilla) consisting 



