EVOLUTION OF MOLARS 



121 



such highly specialized Cricetines as Neotoma, it is very generally, 

 but in my opinion quite erroneously, believed that the Microtinse 

 are more closely related to the CricetinjB than they are to the 

 Murinse. Miller and Gidley ^ indeed form a family Cricetidse 



Fig. 63. — Cheek-teeth of Brachytarsomys albicauda Gunther. 



Crown views enlarged : a, h. right upper, a', h'. left lower molars arranged 

 and lettered to show the homologies of the cusps, a, a', younger and 

 less worn ; h, h' . older and more worn. 



(containing the Cricetinae (including the Nesomyinse), Gerbillinae, 

 Microtina?, and Lophiomyinae) which they distinguish from the 

 MuridiE (containing the Dendromyinse, Murinse, Phloeomyinae, 

 Otomyinse, and Hydromyinse) by the structure of the upper molars. 

 According to them the tubercles of these teeth in Cricetidse 

 * Miller and Gidley, Journ. Washington Acad. Sci., 8, pp. 436, 439, 1918. 



