4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 149 



one another on the occlusal surface, as in P 4 of A.M.N.H. 17137h 

 (fig. 2A). With varying amounts of additional wear the lingual 

 folds generally withdraw from complete penetrance but remain 

 tightly appressed or in close approximation to the external enamel 



Fig. 2. — Right mandibular rami in occlusal aspect of (A), Elasmodontomys 

 obliqtius, A.M.N.H. 17137h; (B), Quemisia grains, U.S.N.M. 253175 (the type) ; 

 (C), Plagiodontia hylaeum, M.C.Z. 35314. 1£ X natural size. 



wall of the tooth through extreme wear, as in Mi and M 2 of 

 A.M.N.H. 17137h (fig. 2A). The labial reentrant generally remains 

 completely penetrant in deeply worn teeth. The dentition of Elas- 

 modontomys in general is discussed in detail by Ray (1964b). One 

 labial and two (major) lingual reentrant folds are present in 

 the lower cheekteeth of Plagiodontia and other Antillean capromyids. 



