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MUSEUM OF COMPARATIVE ZOOLOGY. 165 
METAMYNODON, gen. nov. 
Dentition: I. 3,C.4, Pm. 3, M. $. Upperand lower canines obliquely 
placed, the latter fitting somewhat internal to the former when the jaw is 
closed. The first upper premolar wanting; the second, third, and fourth pre- 
molars are of the molar pattern. Post-glenoid and post-tympanic processes 
widely united. 
Ficure 7. — Skull of Metamynodon planifrons, in side view, about one sixth natural size. 
Metamynodon planifrons, sp.nov. Specific characters. First upper molar 
with an incomplete internal cingulum. Lower median incisors small. The 
molars greatly exceeding the premolars in size. 
This genus is represented by a single skull in fine preservation, and the 
anterior portion of the left mandibular ramus. The latter specimen was found 
some little distance from the skull, but for many reasons may be safely placed 
with it. The canine-incisor formula is the same, and the diameters of the 
canine fangs are similar. There is one less premolar, but the molar-premolar 
series as a whole has the same antero-posterior length. 
Metamynodon is evidently a highly modified successor of Amynodon, of about 
double its size and strength. The dentition is reduced by the loss of one upper 
and two lower premolars. The pattern of the premolars presents a slight pro- 
gression in the complication of the transverse crests of pm? ; but as a series 
they show a decided retardation of growth as compared with the molars which 
assume very large proportions. The mandibular symphysis is relatively 
much narrower. The sagittal crest is still more powerful. Theskull is modi- 
fied by the unusual shortening of the facial region, and the flattening of the 
cranium and broadening of the zygomatic arches, but without the develop- 
