500 THE EOCENE PERIOD. 



onoids, and their superior articular face extends to the coronoid. The ex- 

 ternal expansion is semicircular in outline, and extends to the base of the 

 coronoid anteriorly. The internal expansion is triangular, with the apex 

 decurved and continuous with the posterior edge of the condyle. The artic- 

 ular surface descends on the latter, occupying the interior half of the con- 

 dyle. There is no ridge or tuberosity below the condyle posteriorly as in 

 many perissodactyles. The masseteric fossa is shallow, and only defined by 

 the low anterior ridge. This ceases rather abruptly at the middle of the 

 depth of the ramus below the last molar. The internal pterygoid fossa is not 

 marked. The inner edge of the base of the coronoid is rather prominent. 

 The dental foramen enters a little below the tooth line. There is one men- 

 tal foramen, which is below the first premolar. 



Measurements of skull. 



M. 



Length from canine to foramen magnum, inclusive 089 



Width of skull at base of zygoma 063 



Width of palate between fourth premolars 017 



Length from occipital crest to beginuing of sagittal crest 039 



Length from occiput to line of anterior border of orbits 0C35 



Width at pos'orbital angles 012 



Width at auricular meatus 034 



AVidth of nasal bonces behind (both) 020 



Width of sphenoid at foramen lacerum 010 



Width of foramen magnum 0085 



l)i-l>th of skull (without molars) at front of orbit 034 



Length of mandibular ramus (tot.al) 099 



Length of ramus to base of coronoid 066 



Depth of mandible at condyle 048 



Depth of mandible at coronoid 053 



Depth of mandible at last molar 017 



Depth of mandible at fourth premolar 015 



Depth of mandible at canine 006 



The lower jaw above described belongs to the same individual as the 

 skull, but lacks the condyles. These I derived from a perfect lower, which 

 has the good series of teeth which furnished the description of them already 

 given. For vertebrae recourse must be had to still other specimens. 



The axis and third cervical veriebrce are so much like those of Phenaco- 

 dtis vortmani that the description of them will apply to these. They are 

 somewhat smaller. The inferior keel terminates posteriorly in a tiiangular 

 table with concave middle in both. The articular surfaces are very oblique, 



