526 CENOZOIC TIME — MAMMALIAN AGE. 



some of the Eocene strata, especially the Middle Eocene, as has 

 been mentioned on p. 523. 



In the Miocene, the genus Nummulites — already become extinct — is succeeded 

 by another, similar in the general form of the species, called Amphistegina. 



Mollusks were far more numerous in species and individuals in 

 Europe than in North America. The number of kinds described 

 is about 6000, while not over 3000 American are known. The 

 shells of some localities — as, for example, the Paris basin — often 

 have nearly the freshness of living species, excepting a prevalence 

 of a white color, the original tints being mostly lost. In general, 

 also, the approximation to the living species is close. There are 

 but few Brachiopods (about 40 against 200 in the Cretaceous), and 

 these are almost wholly of the genera Terebratula and Rhynchonella. 



The Vertebrates are the species of highest interest. The order of 

 Teliosts, or common fishes, which began in the Cretaceous, was pro- 

 fusely represented ; nearly 300 species have been named, while only 

 half a dozen or so of ordinary Ganoids, and twenty of Pycnodonts, are 

 known. The Pycnodont group is now extinct. Teeth of Sharks 

 are also common, and are like those of America in genera and 

 partly in species. 



Among Reptiles there were many true Crocodiles, — eighteen or 

 twenty species having been described, to two or three in the Creta- 

 ceous, and seven or eight in the Present period. Turtles were nu- 

 merous ; over sixty species have been described, and the shell of 

 one Indian species of the Miocene — Testudo ( Colossochelys) Atlas — 

 had a length of twelve feet, and the animal a total of nearly twenty 

 feet. The feet must have been larger than those of a Rhinoceros.. 



The first of Snakes have been found in the Eocene. A species 

 twenty feet long, Palceophis typhosus, was discovered in the Brackles- 

 ham beds. Half a dozen species related to the common Black 

 Snake ( Colubridce) occur in the Miocene. 



The earliest remains of Birds, in Europe have been afforded by 

 the Eocene. Out of a dozen species from the Paris basin, two are 

 web-footed and related to the Pelican, three Waders, one Phea- 

 sant, two Perchers, one Owl, two of the Vulture tribe. 



The earliest Mammals of the age occur in the Lower and Middle 

 Eocene, — anterior to those of the Upper Missouri. The Eocene 

 species include from the beginning both Herbivores and Carnivores; 

 but the former greatly preponderate. The Early Herbivores are 

 mostly of the tribe of Pachyderms, and were allied more or less 

 closely to the Tapir (as the Palxoihere and Lophiodon), and Hog (as 

 the Hyracothere and Chceropotamus) ; or partook of characteristics be- 



