ACTINOPODOUS HOLOTHURIOIDEA. 



153 



tions, are scattered all over the perisome but at irregular inter- 

 vals. The minute white spots which cover the dorsum seem to 

 be due to aggregations of these grains. In the pedicels, 1 can de- 

 tect no specially developed supporting rods : there seem to be 

 only X- shaped spicules and minute grains, some of the former 

 possibly somewhat thicker than in other parts. The end- 

 plates are somewhat peculiar : instead of a plate with uniformly 

 close net-work, there are centres of close net-work in the 

 plate, and these are united with one another by looser net- 

 work. 



The calcareous ring is as shown in textfig. 25«. The mouth 

 being ventral, the ring has an oblique position and the pieces are 

 more or less oblique. The dorsal pieces 

 are certainly larger than those of the 

 ventral part. The stone-canal is fastened 

 on the dorsal mesentery and the mad- 

 reporic body is found on the edge of the 

 opening in the mesentery close to the dorso- 

 median piece of the calcareous ring. In 

 one specimen, the proximal part of the 

 stone-canal was distinctly white and cal- 

 careous and seemed even to stick out of 

 the membrane. A membranous duct 

 was formed as a continuation. In an- 



dialii ; Rrd — Right dorsal radialia ; 



other specimen, there was no such pe- Rii_Right lateral radüüia. 

 culiar arrangement. The Polian vesicles are in two bundles, one 

 on each side of the ventral median line. Each bundle starts with 

 a single stem, but soon divides. In one specimen, the right 

 bundle had two long vesicles and one much shorter, which how- 

 ever had several small branches. The left bundle started also 



°?o 



^ 



Textfig. 25. 



Siickopus ananas : a — Calca- 

 reous ring ; h — Minute grains ; 

 c — X-shaped spicule. (h — c x 

 300). Imd — Middorsal interra- 

 dialia ; Ird — Right dorsal interra- 

 dralia ; Irv — ^Right ventral interra- 



