STROBILOPS. 



15 



In Europe about twenty species are known running from 

 the Eocene to the Upper Pliocene. 



The remarkable discontinuity in the distribution of Stro- 

 bilops, and even of its subgenera, will be seen by the accom- 

 panying map upon which the occurrence of the genus is 

 roughly indicated. 



Subgenera 



1. atrobilops s.str 



2. Eostrobilops 



3. Discostrobilops 



4. Enteroplax 



Fig. 2 World in North Polar projection. Tertiary distribution of 



Strobilops represented by dots; Recent by black spots, and Discostrobilops 

 by horizontal lines. 



These small snails attracted attention more than a century 

 ago, the first (Eocene and Oligocene) species having been de- 

 scribed by Brongniart in 1810. Say discovered the first living 

 species in 1817. The genus appears to have been a favorite 

 one with paleontologists; notices of the species, especially in 



