MONOGRAPH OF THE EXISTING CKINOIDS. 519 



a right angle; that between the distal border and the oblique curved proximal 

 border is well rounded, and projects slightly beyond the base of the terminal claw. 

 The cirrus segments are not constricted centrally, and there are no signs of dorsal 

 processes. Another cirrus with nine segments and a terminal claw reaches to 

 the distal two-thirds of the IBrj ; a third with eight segments and a terminal claw 

 reaches to the middle of the IBr x ; and the fourth, with about eight short segments 

 and a terminal claw, reaches to the distal end of the radial in the median line. 

 The fifth cirrus is lacking. The longest cirrus is the left anterior, and the shortest 

 the right posterior. 



From the character of the cirri the identification of this pentacrinoid with 

 any of the comatulids inhabiting the vicinity of Singapore, with the exception 

 of Comatula Solaris, C. pectinata, Heterometra guinduplicava, Stephanometra 

 spicata, S. monacantha, and Lamprometra protectus, would appear to be excluded. 



Judging from what little we know of the pentacrinoids of the species of 

 Comasteridaj the length and slenderness of the column and the relatively large 

 number of columnals would seem to indicate that this specimen can not be the 

 young either of Comatula solans or of C. pectinata. 



The sides of the calyx to the distal borders of the radials are approximately 

 straight, and diverge from the centrodorsal at an angle of nearly 90. 



The presence of inf rabasals can not be determined ; but at this stage, if present, 

 they would probably be united with and concealed by the centrodorsal. 



The basals are very prominent and are about equal in length to the radials. 



The latter are broadly united all around the calyx, their apposed sides being 

 of about the same length as those of the basals. 



The radianal is very large and conspicuous and is entirely excluded from the 

 radial circlet, though the radials subjacent are still separated by a long and very 

 narrow V ; its base, semicircular in outline, runs along the distal third of the lateral 

 borders of the radials and entirely spans the distance between the bases of the 

 IBr! on either side. The lateral borders are slightly convex, the right more so 

 than the left, and converge slightly so that the distal edge, which is almost straight 

 and horizontal and is on a level with the articulation between the elements of 

 the IBr series, is only about two-thirds as long as the base. The reticulation in a 

 transversely oval area coterminous with the proximal border and extending distally 

 for about one-third the length of the plate is much finer than elsewhere. The 

 distal border is more or less rough and denticulate. The plate exhibits no evidence 

 of resorption. 



Except for the radianal there are no plates in the interradial areas between 

 the orals and the circlet of radials. On the basis of our present knowledge this 

 would seem to indicate that this specimen can not belong to any of the species of 

 Comasteridte. 



The orals are about as long as the radianal, but narrower, with a less regular 

 outline. They appear to be deeply dentate distally and deeply depressed in the 

 middle. It is not possible to determine these features satisfactorily, as they are 

 more or less concealed by the arm bases. 

 142140 21 Bull. 82 35 



