Plate 56. 

 Chsetodiadema pallidum A. Ag. and CI. 



1. Actinostome and adjoining part of denuded test. X 2. 



2. Abactinal system of same. X 2. 



3. Abactinal part of odd anterior ambulacrum seen from without. X 3. 



4. Actinal part of same ambulacrum seen from within. X 3. 

 6. Right anterior interambulacrum, laid out flat. X 3. 



6. Primary spine. X 2. 



7. Base of same. X 4. 



