EDENTATA OF THE SANTA CRUZ BEDS. 327 



Compared with P. magnus, the most obvious characteristic of the pres- 

 ent species is its very much smaller size, though there are numerous less 

 striking differences in the teeth and skull structure. The upper canini- 

 form is not placed quite so far behind the anterior border of the maxillary, 

 and the diastema between - and - is also somewhat shorter proportion- 

 ately ; - resembles the corresponding tooth of P. magnus, except in size ; 

 a and A are rather more elliptical and less rectangular in shape and the 

 long axis of each of these teeth is more oblique to the median line of the 

 palate, inclining slightly forward, as well as externally ; * is somewhat 

 the largest of the molariform series, though not much exceeding A in this 

 respect; - is, as usual, reduced in size and, as in the preceding species, 

 has a reniform grinding surface, with deep vertical groove on the posterior 



side. 



MEASUREMENTS. 



Upper dentition, length 048 i, length 0065 



" " " 1-&. 032 " width 0085 



Distance, 1 to anterior border of max- i, length 0065 



illary 019 " width 0095 



Diastema between -i- and % oi I *-, length 0055 



J, length (t. e., antero-posterior diam- " width 0093 



eter) 006 , length 005 5 



1, width (t. e., transverse diameter) 0043 " width 007 



In the skull the resemblance between the two species is very close, but, 

 even disregarding size, there are a number of differences which appear to 

 be characteristic and constant. In P. longirostratus the sagittal area upon 

 the frontals is much narrower and the area and the temporal ridges are 

 better defined. The top of the skull is more nearly horizontal and the 

 descent to the rostrum is much more gradual ; the lachrymal is broader, 

 but less prominent, and the foramen is smaller. The rostrum is shorter 

 and wider and narrows more anteriorly, while the preorbital fossa:: are 

 more distinct ; the nasals are shorter and wider and do not emarginate 



the frontals so deeply. 



MEASUREMENTS. 



Face, length orbit to anterior nares 045 Zygomatic arch, length 086 



Skull, width at postorbital constriction .048 Palate, length in median line 053 



" " " forehead 060 " width in front of ^ 03 1 



over lachrymals 067 " at i 019 



Rostrum, width at preorbital fossae 037 " " * 019 



" " " anterior end 030 



