MESOZOIC ERA. AGE OF REPTILES. 



339 



discussion. This anticipation is fully realized in the Ju- 

 rassic. In England there have been found about eighteen 



species,, and,, in the United States, Marsh has found seven- 

 teen species; so that there are now known about thirty-five 

 species of Jurassic and three species of Triassic mammals. 



