ACTINOPODOUS HOLOTHUEIÜIDEA. 139 



there is a circle of rather small holes around the central open- 

 ing, but in complete ones this circle is often interrupted. The 

 spire is built of four rods with a transverse beam and terminates 

 in a crown with 12 — 10 or more teeth. The buttons (d) have 

 mostly three pairs of openings with the margin decidedly crenato. 

 There are knobs on the middle beam, and very often other parts 

 are also beset with the same. Tlic calcareous bodies in the ventral 

 perisome are plumper than those in the dorsal, so that the 

 holes are smaller. In the small Liu-Kiu specimens there are, be- 

 sides the tables of the same shape, some others with much 

 larger disk but comparatively small crown and with two or more 

 circles of small holes around the central opening in the disk. It 

 seems therefore probable that in this species also the young 

 animals have tables that are larger and more complete than those 

 in the old. 



The anus appears to be stellate, and is surrounded by five 

 groups of small papillœ. Polian vesicle one. Stone- canal, attached 

 to the right of the dorsal mesentery, very large, long and band- 

 like, having the characteristic appearance described by Selenka 

 (1867, p. 333, Fig. 71 x). Its wall contains felt-like fibres which 

 appear to me to be of an elastic nature and not calcareous. 

 Calcareous ring, as shown in a of the textfigure. Even in well- 

 preserved specimens I can not discover any Cuvierian organ, which 

 is probably wanting in this species. 



From the foregoing accoinit two interesting facts stand out : 

 1) the end-plates of both the dorsal and the ventral ambulacral 

 a})pendages are more developed in the yoimg than in the old in- 

 dividuals, and 2) among the calcareous deposits the tables are 

 larger and more completely built in the young than in the old 

 individuals. From the first of these facts, it is not entirely cor- 



