THE TERTIARY PERIOD 



315 



Beetles, Bees, and Ants. The prolific vegetation of the period was 

 of course very favorable for Insect development. 



a b 



Fig. 194 

 Tertiary Pelecypods: a, Venericardia marylandica (Clark 

 and Martin); b, Pecten choctanensis (Aldrich). (After 

 Maryland Geological Survey.) 



In a single Miocene stratum a few feet thick at Oeningen, near 

 the Swiss border, more than 900 species of Insects have been found. 

 "In some places the stratum is black with the remains of Insects. 



a be 



Fig. 195 

 Tertiary Gastropods: a, Fulgur carica; b, Strepsidura 

 subcalarina; c, Turritella potomacensis. (All from 

 Maryland Geological Survey.) 



The same stratum is also full of leaves of Dicotyls, of which Heer 

 has described 500 species. Mammalian remains and also Fishes 



