Vertebrate fauna of the loup fork beds. 31 



The general form of the skull is cameloid, in the compression of the 

 nasal region, and the expansion at the orbits superiorly and posteriorly. 

 The supraorbital foramen is entirely intromarginal and is above the pos- 

 terior part of the orbit. 



The maxillary bone continues posterior to the last molar tooth, one 

 and a half times the length of the latter. The palate is of moderate 

 width, and contracts gradually forwards, becoming narrow posterior to 

 the canine teeth and expanding slightly to the latter. The palatal notch 

 extends as far anteriorly as the posterior border of the penultimate molar, 

 and possibly a little further, as its anterior border appears to be notched, 

 but whether this is normal or not is uncertain. The palatine foramen 

 enters opposite the posterior borders of the penultimate molars. The 

 pyramidal processes approach each other posterior to the maxillary bones, 

 thus narrowing the nareal trough. 



On one side of the skull the five posterior molars are well preserved. 

 The space for the third premolar is shorter than in the P. insignis, and I 

 can not find an alveolus for the fourth, but its position appears to be oc- 

 cupied by osseous tissue. In P. insignis this tooth is distinct. The 

 grinding faces of the crowns are wider tlian long, excepting that of the 

 last, where the proportions are reversed. The protocone is large and 

 well fused with the protoconule, and it is rather more prominent in- 

 wards than the Ii3'pocone, which is not distinct in any of the teeth. The 

 enamel borders are perfectly simple, and there is no loop between the 

 protocone and hypocone. The dentition is not that of a very old ani- 

 mal, as the lakes of the fii-st tM'O molars are perfectly preserved. The sec- 

 tions of the I'OoLs of the canines show that thej'^ were of moderate size. 



The free extremities of the nasal bones are short and acute, and the 

 nareal fissure terminates above the position of the fourth premolar, were 

 it present. 



Measuremeiits . 



Mm. 



Length from posterior border of orbit to extremity of nasal bones 235 



Diameters of orbit \ anteroposterior 53 



{ vertical 53 



"Width of front at middle of orbit 120 



Width of nasal bones above infraorbital foramen 28 



AVidtli of nasal bones at nareal fissure 35 



Length of free part of nasal bones 25 



Length of maxillary bone to canine 227 



Length of maxillary posterior to M. iii 47 



Width of posterior at extremity of maxillaries 24 



Width of posterior at end of last molar 35 



Width of palate at M . i 50 



Width of palate posterior to canine 26 



Diameters of M. i j anteroposterior 20 



j transverse 25 



