272 
The American Geologist . 
May, 189& 
latter (or internal). The para-ancl metacones are, however,, 
proportionately better developed in the type, the metaconer 
being quite small in T.ferox. In all cases the paracone is the 
larger. The protocone offer ox is more pyramidal and robust 
and is surrounded by a greater cingulum. The transverse 
diameter of the anterior portion is equal in both species, but* 
the diameter of the posterior is less in the type, due to the 
inward posterior inclination of the external edge. Again the 
anterior and posterior edges are parallel in T. ferox, but in 
the type species the anterior edge converges toward the inter¬ 
nal, making thereby, as stated above, the external diameter 
greater than the internal. 
In the inferior dentition of T. altigenis the incisors, canines,, 
and first premolar and in T.ferox (fig. 3) part of the incisors 
and the first premolar are missing. In the former species the 
dentition from i>7~2 to mT2 measures 66 mm. and in the latter 
90 mm. The canines have an antero-posterior diameter of 
19 mm., transverse 10 mm., and a height of 38 mm. They curve 
backward and are placed external to a line drawn along the 
external bases of the p. m-m series. pT 2 is a simple tooth of 
equal height in both species, but one-third greater in antero¬ 
posterior diameter and one-fourth in transverse than in the 
type; this difference is not due to a greater development of 
the cone in T.ferox, but to a more elongated crown, giving 
rise to a minute heel. FTs is also a simple tooth of propor¬ 
tionately slightly greater development over the type tooth. 
p 71 of T. ferox has a greater transverse diameter over the 
antero-posterior than in the type and is one-fifth greater in 
length and one-half in width. The height of the protoconid is 
the same in both species and hence is proportionately some¬ 
what greater in height and is more distinctly separated from 
the latter cone than in ferox. A minute cusp (of rather rare 
occurrence) is formed on the talon or heel, but is absent in 
the type species. This cusp is separated from the proto- 
conid by a sharp groove. The contour of the crown of 
mTi is more regular, the centres not being compressed and 
there is a greater upward curve under the main cone. 
The paraconid has the usual sharp elongated surface pointing 
inward; the proportionate heights, if compared with those of 
the protoconid, indicate a greater development in T. ferox - 
