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CLARK: RECENT CRINOIDS 



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Fig. 3. Thermal distribution of the families of recent crinoids; the zone of 

 maximum representation is between 55° and 65°, especially between 60° and 65°; 

 it is probably within these temperatures that the very rich post-palaeozoic fauna 

 was developed. 



families between 60°-65°, in the Macrophreata between 55°-65°, 

 the number in the case of the famihes of the Oligophreata 

 diminishing gradually as the temperature increases, and the num- 

 ber in the case of the Macrophreata decreasing gradually as the 

 temperature diminishes. * 



Examining the total for all the comatulid families, we find the 

 largest representation between 55° and 65°, with the emphasis 

 between 60° and 65°. The only stalked crinoids of which we have 



