254 PATAGONIAN EXPEDITIONS I PAL/EONTOLOGY. 



MEASUREMENTS. 



Upper dentition, length 0425 , width 006 



" " " i-6- 025 Lower dentition, length 0335 



i, length (i. e., antero-posterior di- " " " z _ 4 023 



ameter) 0075 T> length 0045 



" width (/. e., transverse diameter) . . . .004 " width 004 



1, length 005 j, length 0065 



" width 007 " width 008 



2, length 007 - s> length 0065 



" width 0085 " width 008 



A, length 007 ? , length 007 



" width 008 " width 007 



A , length 003 



As already remarked, the skull has a highly characteristic appearance. 

 The cranium is long, broad and quite low, the upper contour rising but 

 slightly from the summit of the occiput to the inconspicuous parietal emi- 

 nence ; the postorbital constriction is long, but not deep, the forehead is 

 gently convex and the preorbital region, or rostrum, unusually long, 

 narrow and tapering. It is this elongate, tapering rostrum which, more 

 than any other feature, gives its peculiar appearance to the skull. The 

 sagittal crest is feebly developed and only upon the frontals in the region 

 of the postorbital constriction. The occiput is low and broad, somewhat 

 inclined forward, and decidedly convex in both directions, with a median 

 prominence which lodges the vermis; the condyles are quite large and 

 prominent, but the paroccipital processes appear to be entirely obsolete. 

 In marked contrast to nearly all the other species of Hapalops, the supra- 

 occipital is hardly at all reflected upon the dorsal side of the cranium. 

 The parietals, which are large, have no sagittal crest, but, on the contrary, 

 a well defined groove along the sagittal suture, and an ill-defined sagittal 

 area, which is broadest in the middle and narrows both before and 

 behind. The zygomatic process of the squamosal is much swollen at the 

 base, indicating an unusually large sinus. The tympanics, frontals and 

 lachrymals do not differ in any significant way from those of the other 

 species of the genus. The nasals are narrow and elongate; they are 

 broadest at the frontal suture and narrowest about the middle of their 

 course, expanding again at the anterior end, where they show the usual 

 lateral notches. The maxillaries have an elongate facial portion, in front 

 of the orbits, and the preorbital fossae are very shallow ; the hard palate 



