198 NEW YORK STATE MUSEUM 



It would appear that the final stages of the development of the 

 agelacrinites had taken diverse courses, one through Agela- 

 crinites into the Lepidodiscus-Discocystis line to extinction (L. 

 alleganius,D. kaskaskiensiSjL. squamosus), the 

 other into the expression of A g e 1 a c r i n u ,s b u 1 1 s i, b 1 a i r i, 

 etc. which bear the stamp of the initiatory phases of the race. 



Various writers have been disposed to separate the agelacrin- 

 ites from the Oystidea, Billings having first introduced a dis- 

 tinctive name for the entire group, Eidrioasteroidea, Jaekel pro- 

 posed (1895) to term essentially the same group, Thecoidea. Of 

 the subdivisions of this class the family Agelacrinitidae is well 

 defined, though its members and their genetic relations are still 

 promising subjects for study. 



