ORDINAL TYPES OF MOLARS: CHKIROl'TKII A 



129 



CHEIROPTERA. 



The following quotation may be made from the writings of an 

 author (Oldfield Thomas) who is in no way committed to the tri- 

 tubercular theory; it becomes especially clear by reference to the 

 preceding section on the Insectivora : 



"The earliest Bats, or rul;i-ochimptera \vuuld liave been cuspi- 

 date-toothed and insectivuroiis like their ancestors the terrestrial 

 Insectivora. Among them there would presently have arisen a 

 form like Harpyia, fruit-eating but still with cuspidate teeth and 



* 





FIG. 81. Skull, crown view of uppi.-r to-th and internal view of right upper canine of Pteralopex 

 i/t,-nta Thomas, a Fruit-Bat, which, instead of having cusp-less cheek teeth as in other Mega- 

 cheiroptera, has retained cuspidate teeth more or less suggestive of the tuberculo-sectorial type. 



x L. After Oldfield Thomas. 



no doubt markedly ' tuberculo-sectorial ' premolars and molars. 

 Then, while the modern J In //>// i" would have arisen in one direction 

 by the reduction of the incisors, in another there would have 

 followed some form like Ptcralopex, still retaining to a certain 

 extent cuspidate teeth. Then the cusps would have more and 

 more tended to disappear, the result being Pfi rn/n^ and its allied 



i 



