163 SPOLIA ZEYLANJCA. 



other three sub -genera, and that Bohadschia is the more 

 primitive form. The genera Argiodia, Halodeima, and 

 Thymiosicya are united on the common ground of similarity 

 of spicules and calcareous ring, 



I show the relationship of the sub-genera in the following 

 diagram : — 



Thymiosicya 



Argiodia 



Halodeima 



Acfcinopyga 

 Bohadschia 



I give below the diagnoses of the genus and the sub -genera. 



Genus HOLOTHURIA. Linn. 



(= Mulhria, Jager 1833 + Holothuria, Linn. 1758.) 



Usually twenty peltate tentacles, exceptionally more or less. 

 Ambulacral appendages, pedicels alone, papillae alone, or with 

 both. A single bundle of genital tubes on the left side of the 

 dorsal mesentery. Calcareous ring without posterior pro- 

 longations or long retractor muscles. Cuvierian organs often 

 present. Anal teeth sometimes present. 



