ASTEKOIDEA OP H.M.S. ' CHALLENGEB ' EXPEDITION. 251 



radiation apart being very slight. No definite order is maintained 

 in the arrangement of the paxillge. The papulae are small and 

 dark brown, or almost black in colour, and a broad space occurs 

 along the median line of the ray in which none are present. In 

 the centre of the disk there is a large, conspicuous, and well- 

 developed conical prominence, upon and in the neigbbourhood of 

 which the paxillge are greatly reduced in size. No anal puncture 

 is traceable. 



The madreporiform body is small and situated at about one 

 third of the distance from the margin to the centre of the disk. 

 The terminal (ocular) plate, though small, is conspicuous and 

 elongately oblong. 



Colour, in alcohol, umber-brown, becoming lighter in shade 

 towards the extremities of the rays. The spinelets white. Small 

 specimens yellowish white. 



Station 232. Lat. 35° 11' N., long. 139° 28' E. Depth 345 

 fms. ; bottom temperature 5°'0 C ; sandy mud. 



ASTEOPECTEN POLTACANTHirs, Muller ^ TroscTiel. 

 Station. Port Jackson, Australia. Depth 2-11 fms. 

 Station. Admiralty Island. Depth 16-25 fms. 

 Station. Yokohama, Japan. Depth 5-25 fms. 

 Station. Kobi, Japan. Depth 8-50 fms. 



ASTEOPECTBN PECTINATITS, n. Sp. 



Eays five. i2<3"5r; i2=48 millim., r=14 millim. Eays 

 broad at the base, tapering continuously to the extremity, whicb 

 is finely pointed. Breadth of a ray at the base 16'5 millim. In- 

 terbrachial angle subacute or very slightly rounded. 



Supero-margiaal plates 21 in number from the interbrachial 

 line to the tip, higher than broad, the disparity being greatest 

 in the arm-angle and diminishes towards the extremity. When 

 seen abactinally the plates have the appearance of being slightly 

 oblique in relation to the direction of the ray, and each, excepting 

 the two innermost, is slightly convex or submammillate at the 

 outer augle formed by the junction of the dorsal and lateral 

 superficies of the plate, which falls in the marginal contour of 

 the ray. On the summit of this convexity is borne a small short 

 conical spinelet ; and although normally the series of spinelets is 

 continuous throughout the ray, a plate occasionally occurs on 

 which the spine is wanting. The two inner supero-marginal plates 



