80 



MICROTIN^ 



spine, and tunnelling under the postero-lateral bridges we would 

 convert the palate of Prometheomys into one like that of Microtus. 



Fig. 5\.— Prometheomys schafoschnihowi Satunin. 



Skull and left mandibular ramus dissected to show the alveolar courses 



of the teeth (enlarged). 



The pterygoid fossae are fairly large but are not deep, their floors 

 being about level with the ventral surface of the basisphenoid ; 



