THE ILLINOIAN ICE INVASION 



343 



The biota of the Sangamon interval is the most extensive and varied of 

 any of the interglacial intervals, 314 species being known, divided as follows: 





Living 



Extinct 



Total 



Plants 



65 



132 

 2 

 2 

 6 



3 



1 







83 



20 



68 



Mollusks 



133 



Crustacea 



2 



Insects 



85 



Vertebrates 



26 







Total biota 



207 



107 



314 







The plants were abundantly represented, the Pinaceae (8) andFagaceae (8) 

 leading in the number of species. The large number of deciduous species 

 present is noteworthy. The molluscan fauna was very extensive, embracing 

 nearly all of the families inhabiting the temperate regions. The number of 

 pelecypods is also noteworthy, the two families totalling 35 species. The 

 number of pulmonates (60) is also striking, as is the number of species in the 

 genus Polygyra (17). The plants and mollusks are practically the same as 

 those now living in the same region; among the insects, however, all but 2 

 are extinct. The insects all belong to the order Coleoptera, or beetles, and 

 of these the families Carabidae (41) and Staphylinidae (20) contain the greatest 

 number of species. Of the vertebrates, 20 or about 77 per cent are extinct. 

 Nearly all of these belong to the order Mammalia. As in Yarmouth time the 

 sloth, horse, elephant, mammoth, peccary, bison, musk ox, giant beaver, and 

 many deer roamed the woods and plains. Bear and wolves were also present. 



