402 



HISTORICAL GEOLOGY 



but the ichthyosaur, having lost the power of resorting to the 

 shore to lay its eggs, was in the habit of bringing forth its 

 young alive, as is proved by the interesting find of five little 

 ichthyosaur skeletons undamaged within the skeleton of one 

 of these reptiles. 



FIG. 421. A family of fish reptiles (Ichthyosaurus). (Painted by C. R. 

 Knight, under the direction of Professor H. F. Osborn. Copyright by 

 Amer. Mus. of Nat. Hist.) 



Mammals make a feeble beginning. Were it not for the 

 overwhelming predominance to which the mammals after- 

 wards attained, their first appearance would be scarcely worth 

 mentioning. In the Triassic rocks a few little bones have 

 been found which seem to be those of primitive mammals. 



