PLATE VI. 

 Callidebma mosaicum, Forbes, sp. (P. 9.) 



From the Grey Chalk. 



Fia. 



1. Abactinal aspect of an example from which the abactinal plates have been 



removed ; natural size. (Coll. Brit. Mus.) 

 2 a. Abactinal aspect of another example from which the abactinal plates have 

 been removed, showing the inner surface of some of the actinal intermediate 

 plates and adambulacral plates ; natural size. (Coll. Brit. Mus.) 

 /). Adambulacral plates, seen from within ; magnified, 

 c. Actinal intermediate plates, inner surface ; magnified. 



