30 



MICROTIN^ 



that of the more primitive Muridae in its general lightness and 

 delicacy of construction, in the persistence of the median sutures, 

 the flatness of the palate, the wide separation of the temporal 



Fig. 18. — Brachytarsomys albicauda Gunther. 



Dorsal, ventral, and lateral views of skull, enlarged ; the small figure 



shows the skuU in dorsal view, natural size. 



ridges, and in many other respects. The upper incisors when 

 unworn retained distinct traces of their original cuspidate crowns 

 (see pp. 99-101). The lower incisors were wholly lingual or 

 inferior to the molars in position; they were very short, so that 

 they did not extend further back than to a point opposite the 



