24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



The cheekteeth are oj^en at the base, as in Elasmodoutoinys of the 

 same age ; whether or not they eventually become closed as in adult 

 Elasmodontoiuys cannot now be determined. The enamel pattern is 

 fundamentally the same as in Elasiiiodoiifoiiiys, that is, a pentamerous 

 pattern in which all the reentrant folds have been extended nearly or 

 quite across the crown ( the outer fold passing behind the second inner 

 fold). The posterior limb of each fold has been thickened to form a 

 conspicuous enamel plate and the anterior limb of each fold except 

 the first has been reduced to the vanishing stage. As compared with 

 that of the Porto Rican animal the pattern in Queuiis'ia shows a 

 mixture of excessive peculiarity and less high specialization. The 

 forward turning of the enamel folds so that the anterior portion of 

 each fold is approximately parallel with the main axis of the toothrow 

 is a specialization of high degree and very peculiar kind. In 

 lilasuiodoutomys there is an indication of this tendency at the front 

 of the premolar, but the direction of the folds in the molars is normal 

 and not essentially different from that seen in Plagiodontia, Isolobodon 

 or Aphcutreus. On the other hand the process of plate specialization 

 has not progressed so far in Qiiciiiisia as it has in Elasiiiodoiitomys. 

 While the external reentrant fold has extended completely across the 

 crown in all three of the used cheekteeth neither of the two internal 

 folds has cjuite reached the enamel of the opposite side in pui^, and 

 only the first has penetrated so deeply in iiii and uio. In each of the 

 molars there is, therefore, one incomplete enamel plate, the second, 

 while in the premolar there are two, the first and second. In 

 Elasiiiodontoiiiys all the folds have crossed the crown in all the teeth, 

 and there are, consequently, no incomplete plates. The peculiar twist- 

 ing of the enamel pattern almost into the axis of the toothrow in 

 Oucinisia throws the anterior loop of each tooth over on to the inner 

 side of the crown out of contact with the tooth in front of it. The 

 free face of each of these loops carries a fully developed enamel 

 wall. In Elasmodontomys such an enamel wall occurs on the first loop 

 of the premolar only. 



A fragment of incisor (apparently an upper tooth) 19 mm. in length 

 has a width of 5 mm. and an antero-posterior diameter of 4.2 mm. at 

 level immediately proximal to the terminal worn area. The anterior 

 face is longitudinally fluted by six obscurely developed ridges and the 

 faint intervening concavities. 



A broken femur which I refer without much doubt to this species 

 differs from the corresponding bone in Elasmodoutoinys obliquus in 

 the conspicuous flattening of its shaft. The greatest and least diameters 



I 



