INTERRELATIONSHIPS OF GENERA 



69 



tall-crowned, their alveolar capsules rising high in the floors of 

 the orbit and sphenorbital fissure. The enamel is differentiated 



Fig. 42. — Lagurus luteus Eversmann. 



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

 shows the skull in dorsal view, natural size (B.M., No. 12.4.1.121; 

 the median dorsal suture is quite obliterated in thia specimen). 



as in Microtus, but the re-entrant folds lack cement. The 

 enamel pattern is characterized by the great width of the re- 

 entrant folds, perfect alternation of the salient angles, long- 

 drawn-out appearance of the teeth, and usually by the retention 



