284 PATAGONIAN EXPEDITIONS: PALEONTOLOGY. 



the anterior crest is curved and terminates internally and externally in 

 elevated points, concealing the valley in side-view ; - resembles 3 -, but is 

 smaller and more constantly oval and - is quite small. The teeth are 

 somewhat oblique to the median line of the palate and the two series are 

 nearly parallel. 



In the mandibular dentition, which is known only from the type, T is 

 very small, cylindrical, horizontally abraded, and separated from - 2 - by quite 

 a long diastema ; - 2 - and ^ are transversely oval, more compressed antero- 

 posteriorly and less rectangular than in A. inversus, and T is less cylindrical 

 than in the latter and more obliquely elliptical. 



MEASUREMENTS. 



Type. No. 15,561. No. 15,163. 



Upper dentition, length .0605 .0545 



<< " " 2.-0. 041 .042 .037 



" " " 3.-A 030 .030 .027 



-L, length (i. e., antero-posterior diameter) .006 -0055 



" width (i. e., transverse diameter) .005 .005 



3., length 008 .0085 .008 



" width 008 .008 .008 



-, length 008 .007 .008 



" width 013 .0145 .014 



A length 0075 .007 .007 



" width 012 .0125 .012 



4, length 006 .007 .007 



"width 0095 .0115 .0115 



The dimensions of the lower teeth are all taken from the type. 



Lower dentition, length 052 ^, width 013 



" j_ 034 3, length .007 



T , length 005 " width 012 



" width 005 T , length .on 



j, length 0075 " width oio 



Skull (Plates XLVII, XLVIII).- -The general appearance is quite like 

 that of the larger species of Hapalops, but with many minor differences. 

 The occiput is relatively high and from its summit to the parietal emi- 

 nence the rise is slight and from the eminence to the coronal suture, the 

 lowest point of the cranium, is a slight descent ; from the coronal suture 

 is an almost imperceptible rise to the interorbital region and thence a very 

 gentle descent to the muzzle, which is quite high dorso-ventrally. The 



