ACTrxoroDors holothuiuoidea. 



197 



Calcareous ring is well developed (textfig. oCxi). When looked 

 at from the outside, it looks simply like a plain ring -.vitli some 

 indentations, but when it is pulled outward so as to show the in- 

 side a little, processes become visible. Polian vesicle one, on the 

 left ventral interradius of the circular canal. Genital organs 

 two, ])ushy, one on eacli side of the dorsal mesentery. Cienital 

 papilla distinct in the median dorsal line. The stone-canal opens 

 with several openings near the base of the genital papiha. 



Calcareous deposits are as pointed out by Theel, comprising 

 large wheels, small wheels, cruciform bodies, and spinose spicules. 

 Large wheels are largest in dorsal papilla?, 0.180 — 0.220 mm. in 

 diameter, with eight or rarely nine spokes and four central holes 

 {!>) ; those in lateral pedicels, 0.120 — 0.104 mm. In dorsal and 



^'■UvM'-tAJ 



-^ 



?/ V * 





Textfig. 36. 



I.oimoijfme vlvlacpa : a — Cnlcareo-js ring : h — Lnrge wheel of dorsnl popilln : <• — Middle- 

 sized wheel of dorsal perisorao ; d — Smnll wheel of doisnl pnpill.i ; c — Spinous spicule of 

 dorsnl perisome ; / — Cruciform body of ventrrtl perisome; ;/ — Supporting rod of dorsnl pnpilln ; 

 h — Spinous rod from genitnl tubes, ('j— Ax 200). I — Interrndinlin ; K- — Endinlin. 



ventral perisome, large wheels are few and scattered, cruciform 

 bodies being most numerous. The large wheels are relativelv 



