PLATE XXX. 



Clypeaster subdepressus. 



1. (Upper figure.) The lower floor is removed, to show the course of the alimentary canal, 



I, ?', to its reflex point, i", where it runs to i, and ends at o", the anal opening ; 

 0, 0, 0, 0, ovaries forced to the lower floor ; i; vessel following course of alimentary 

 canal ; g, line of contact of adjacent pyramids of jaws ; j, lateral edges of same ; 

 j°, pits for auricles. 



2. (Lower figure.) Section to show interior of lower floor, the alimentary canal and jaws 



removed ; o, ovaries ; a", auricles ; a, a, a', median ambulacral tube ; a", a" , a", a", 

 lateral ambulacral plates ; i", i", interambulacral plates ; j, circular ring ; p, par- 

 titions ; a", aual opening. 



(Both Figs, natural size.) 



The Drawings are made from preparations by A. AGAS5IZ and JAMES E. MILLS. 



