MAMMALS OF THE MESOZOIC PERIOD 



belonged to small mammals. In Fig. 136 two 

 of these very ancient mammalian jaws are 

 figured. 



Fig. 136. — Lower jaws of tlie ancient Mammals, Dromatherium 

 (upper — Trias), and Dryolestes (lower — Jiirassic), mag- 

 nified about 2i times linear. 



189 



