Iit4 
OX THE STRUCTURE AND CLASSIFICATION 
, 1 ns to the generic separation of Amplutylua from 
formulas are the same, and the molars in each 
AmphileMtes. Althou^n ^ specific 
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articular portion of the jaw. 
PH.A,SCOLOTHERIUM. Plate VIII, fig. 3. 
.Ithoimh the single specimen representing this genus has been long knoivn and 
oftcm d s b^ed, a revi^v of its principal characters is necessary here. While .sepa- 
tZ tZ AnyJuIestes and AmykltyU. by its mandibular characters -d the entire 
absence of teeth of the premolar pattern, it is nevertheless clearly related to the line 
of these genera and of Triconodon, by the character of the molar crowns 
Tlie^-enus is known from a single, well-preserved, right mandibular ramus 
from tlie Stonesfield Slate, the size and proportions of which indmate a strong animal. 
Tlieaimle and condyle are confluent, the former presenting a widely inflected border 
wliicli has been partly broken away. The condyle is on a level with the molars ; it 
faces backwards and is rather broad transversely ; above this the border is deeply 
notched and rises into the powerful, recurved coronoid process. The coronoid has a 
decided anterior rim which sinks below the alveolar border. In the lower part of the 
deep pterygoid fossa, thus bounded, is the dental foramen, and below this, the 
myloliyoid groove stretches forward and sinks beneath the fifth molar. The in- 
ferior border presents a single curvature from the condyle to the symphysis. The 
svmplivsial surface is partly fractured. The incisor border is elevated and the molar 
iKirder depressed. 
Close to the fractured symphysis, the fang of h can be distinguished. The me- 
dian incisor was apparently the largest, and the series decreased in size slightly 
towards the canine. The incisors are semi-procumbent, with long, straight fangs, ex- 
])anding very slightly at the summit into a flattened crown, distantly resembling those 
of Amhlnfherimn and Phascolesies, but quite different from the Triconodon incisors. 
The canine is erect, slightly recurved at the summit, and implanted by a stout cylin- 
drical fang. The first molar is separated by a diastema from the canine and by a 
narrower interval from m^. A close study of mi shows that it possesses, in miniature, 
the characteristic features of the other molars, three cusps and a basal cingulum. 
^^'c observe in other mammals of this period as many as six, seven and eight true mo- 
lars ; tlierc is, therefore, no ground as regards number, either for describing the ante- 
rior tcetli of this series of eight as premolars, or, for calling this genus “ typo dentate.”^ 
Tlie fact that there are seven teeth of uniform pattern, when considered with the 
unusual ])rcscnce of a diastema behind the canine and the comparatively short space 
* Mr. Lydekker in a letter to me, May, 1887. 
* Mesozoic Mammalia, p. 115. 
