

Eliminating the highly variable organic matter and recalculating to too > . the anah i 

 ime the following form : 



rodiscus Chondromttra / . 



[O >.00 



[ 00.00 



■keleton of Zygometra microdiscus contains the highest percentage of MgCO, of 

 any <>f which analyses have been made. The percentage of MgC0 8 in the ikeleton of Chondro- 

 metra rugosa is what would be assumed from the temperature of its habitat. 



