KEPOET ON THE ASTEEOIDEA. 191 



sists of a marginal series of three delicate, rather long, subequal spinelets, the margin of 

 the plate forming a slightly angular projection into the furrow, and the middle spine is 

 placed on the summit of the angle. External to these on the surface of the plate are 

 usually two. (s onetimes three) subequal and rather shorter spines, which may form with 

 the adoral spinelet of the marginal series an obliquely transverse lineal series, or may 

 stand directly behind each of the outside spinelets ; and behind these is a third series 

 of about three short spinelets parallel to the furrow. The second and third series are not, 

 however, always regular in their number and posture, and additional spinelets may be 

 present ; furthermore, the whole of these spines are so closely placed that the armature 

 has generally more or less of a tufted or grouped appearance, which makes it usually diffi- 

 cult to define the true order of their disposition. 



The mouth-plates are elongate and narrow. Their armature consists of a marginal 

 series of twelve to fifteen small spinelets similar and equal in length to, but slightly more 

 robust than, the spinelets of the adambulacral armature, on the inner part of the plate, 

 but diminishing slightly as they recede from the mouth. On the actinal surface of the 

 plate is a lineal series of uniform spinelets running parallel to the median suture. 



The actinal interradial areas are large and extend nearly half-way along the ray, that 

 is, as far as the ninth or tenth free adambulacral plate. They are occupied by intermediate 

 plates bearing large well-defined, well-spaced paxillse, which form transverse series 

 between the adambulacral and marginal plates. The paxillae are composed of delicate, 

 rather elongate spinelets, a little smaller than those borne on the adambulacral plates but 

 larger than those on the infero-marginal plates. The spinelets radiate at an angle of about 

 45° or more to the perpendicular and form an expanded crown. The column or pedicle 

 of the paxillae is not cylindrical but more or less flattened and elongate in the direction 

 obliquely transverse to the median line of the ray. 



There is no modification in the central region of the disk, and I have been unable to 

 detect the presence of an anal aperture. In one example there is, at a considerable dis- 

 tance from the centre, what seems to me a deceptive appearance of a pore, but from its 

 position and character I do not consider it to be an anal orifice. Even if it should ulti- 

 mately prove to be a pore, I should not suspect from its general appearance that its 

 function was anal. It may perhaps be a malformed or altered papular orifice, or it may 

 be accidental. 



The madreporiform body is small and placed near the margin, being less than its own 

 diameter distant from the supcro-marginal plates. In smaller specimens it appears to be 

 rather further away. The striations are comparatively coarse, and several radiate as 

 straight lines from the centre to the margin of the body, the intermediate striation being 

 likewise often straight and short, resembling to a certain degree the septa of a coral. 



The ambulacral tube-feet, though tapering, have a small rounded terminal knob. 



I have failed to detect any pedicellaria> whatever. 



