468 PROCEEDINGS OF THE NATIONAL MUSEUM. 



cusps there is a distinct reentrant angle. Another small reentrant 

 angle lies at the posterior base of the outer cusp. ^ The second ridge 

 is practically a repetition of the first, except that the reentrant angle 

 between middle and inner cusps is broader and not as deep, while that ; 

 at posterior base of outer cusp is better developed. There is also a ii 

 rudimentary reentrant angle at front of outer cusp, so that the | 

 resulting form of the cusp is an imperfect trefoil with a large median j 

 lobe, a posterior one of nearly the same size, and a minute anterior i; 

 seo-ment. In the type the process of attrition has extended far enough 

 to'imite the median ridge with the posterior along the inner edge. \ 

 Third ridge with median cusp larger than in either first or second, ,; 

 the outer cusp rather smaller than that of first or second, and inner \ 

 cusp obsolete. There is a distinct reentrant angle at posterior base I 

 of outer cusp. Second upper molar: Anterior ridge represented by ^^ 

 a laro-e inner cusp and a minute outer one, both joined in present | 

 state of wear to front of main cusp of second ridge. Second like (I 

 that of iirst tooth, Init with outer cusp smaller and lacking the anterior ^ 

 limb of the trefoil. Third ridge as in anterior tooth. Third irpp&r^ 

 molar: Anterior ridge represented ])y a large internal cusp, as well'' 

 developed as that of middle tooth, but quite distinct from second 

 ridge. Second ridge formed by a simple, transverse loop, nar- 

 row on the inner side, but expanding externally to a rudimentary 

 median cusp. Third ridge consisting of a single large cusp, prolialjly 

 the median. It is fully as large as the median cusp of the other teeth. 

 First lower molar: This tooth consists of three very similar bilobate 

 cross ridges, slightly convex or concave in front, deeply concave 

 behind. The anterior is somewhat concave anteriorly and is preceded 

 by a small median tubercle. A similar Init rather smaller tubercle 

 lies between first and second loop on outer side, and a still smaller one 

 between the same loops on inner side. Posterior loop like second,! 

 except that there is a small reentrant angle on outer side. It is fol-' 

 lowed by a median tubercle, rather larger than that at front of tooth. 

 Second lower violar: Essentially a duplication of the second and third 

 loops and posterior tubercle of first tooth, but anterior lobe w4th a 

 rudimentary external tubercle and reentrant angle on outer side of, 

 second lobe deeper. Third loiver molar: This tooth is reduced to an 

 anterior loop about like that of middle tooth, and a broad, crescenti( 

 posterior loop, the slightly concave side of which is directed forward, 

 Measurements. — External measurements of type: Total length, 534 

 head and body, 236; tail, 298; hind foot, 41 (38.6). 



Cranial measurements of type: Greatest length, 49.6; basal length 

 44.6; basihu- length, 42.6; palatal length, 22; least width of palat( 

 between antei'ior molars, 4.8; diastema, 14.6; length of incisive fora 

 men, 6.8; combined breadth of incisive foramina, 3.2; length of nasals 

 18; greatest combined breadth of nasals, Q.Q] zygomatic breadth, 25 



