Xo. 475] 



REVISIOX OF COMPTONIA 



517 



and to those from Switzerland which lleer referred to rolleana and 

 aventica. 



These variations while somewhat wide in their extremes include 



reference to a single sjiccic-, especially wlicn wc cdiividcr the dura- 

 tion of this form from the Koccnc thvou-'h the Miocene, during 

 which time it spread all over Kurope and possihlv to America as 

 well. 



