314 PATAGONIAN EXPEDITIONS! PAL/EONTOLOGY. 



ward; the sigmoid notch is narrower and deeper and the coronoid pro- 

 cess is somewhat narrower and more recurved, and the postero-external 

 opening of the dental canal has a somewhat more inferior and anterior 

 position. The predental beak is considerably longer than in P. cristatus, 

 but its dorsal border does not, as in the latter, rise above the level of the 

 teeth, and the contour of the chin is quite different, rising less steeply 

 from the ventral border, with its anterior part continued forward more 



horizontally. 



MEASUREMENTS. 



Mandible, length from angle 105 Mandible, distance angle to T 053 



height of condyle 039 length of predental beak 023 



" " coronoid 049 " depth of ramus below ^ 023 



distance condyle to ? 045 breadth over angular processes .05 i 



The cervical vertebrae are very small ; they resemble those of the 

 smaller species of Hapalops, but are more delicate, with more slender 

 transverse processes and neural arches, and short, weak neural spines. 

 The thoracic vertebra:: are quite characteristically different from those of 

 Hapalops; in the anterior part of the thorax the vertebrae have very 

 small centra, which increase posteriorly in size, but this increase is rela- 

 tively less than in Hapalops ; only on the centrum of the last thoracic are 

 the ventral foramina visible. The most peculiar feature of these vertebrae 

 is the form of the neural spines, which throughout the region vary little 

 in size, shape and inclination ; as compared with those of a small species 

 of Hapalops, they are much shorter, more slender and more steeply 

 inclined. The small, uniform size and almost unchanging degree of 

 inclination of the spines give to this vertebral column an appearance 

 which is conspicuously different from that of most of the other Santa 

 Cruz Gravigrada. The transverse processes are very short; the zyga- 

 pophyses do not differ from those of other members of the family, the 

 accessory pairs appearing on the last two thoracics. 



The only lumbar preserved, and in an incomplete state, is the first ; in 

 this the ventral foramina are much more conspicuous than on the last 

 thoracic. 



Of the two incomplete caudal vertebae found with this specimen, one 

 is from the anterior part of the tail, probably the fourth or fifth of the 

 series, and the other is from the hinder portion ; these vertebras indicate 

 a tail very similar in its proportions to that of Hapalops. 



