CENOZOIC TIME TERTIARY. 



901 



1511. Besides these, Scudder lias made out 31 species of Arachnids or 

 Spiders. He states that about a fourth of all the species at Florissant are 

 Ants (Formicidse), and that by 1885 more than 4000 specimens of Ants had 

 been brought from the beds. Of Aphides, or Plant-lice, an eighth of an inch 

 long, or less, he has collected over 100 specimens, representing 32 species, 

 and all but one showing well the wings. Two other localities, affording 

 similar species, one on the crest of the Roan Mountains in western Colorado, 

 and the second on the lower part of White Kiver, at the Utah line, are 

 supposed to be at least as rich as Florissant. 



Eocene Vertebrates. 1. Fishes. — The remains of Ganoid fishes (genera 

 Lepidosteus, Amia), and Teleosts, of the Perch, Herring, and other families, 

 are abundant in the Green River shales, along with remains of Plants and 

 Insects. The marine Tertiary beds of the Gulf and Atlantic borders, and. 

 especially of the Eocene, contain, in many places, the teeth of Sharks in great 

 numbers ; three kinds are represented in the accompanying figures. Some 

 of the triangular teeth of Carcharodon megalodon Ag. (resembling Fig. 1513), 

 are six inches broad at base and six and a half long. 



1513-1516. 



1514 



r^ 



1516 



Teeth of Sharks. — Fig. 1513, Carcharodon angustidens ; 1514, Lamna elegans ; 1515, Notidanus iirimigenius. 

 Testudinate. — Fig. 1516, Testudo brontops (X t\s). Figs. 1513-1515, Agassiz ; 1516, Marsh. 



2. Reptiles. — The Tertiary Reptiles include species of Crocodiles, among 

 them, Crocodilus Elliotti Leidy, from South Carolina, and C. Squaiikensis of 

 Marsh, from New Jersey ; of Snakes, of the genus Dinophis Marsh, from 

 Kew Jersey, and of Boavus and Lithophis, from Fort Bridger, about 20 feet 

 long ; of Turtles, of the genera Testudo, Emys, etc., from the Atlantic border 

 and the Rocky Mountain region. Fig. 1516 represents one of the largest of 



