462 Bulletin American Museum of Natural History. [Vol. XXXIV, 
throughout of similar type to those of Absarokius, only much less exagger- 
ated. 2 
The molars are characterized not only by their great width, the first and 
second being as wide as long or wider, but by the approximation of the outer 
cusps towards the centre of the tooth, and the unusual height, not of the 
cusps which are low, but of the crown of the tooth as a whole, especially 
when viewed from the external side. The paraconid is distinct on m,; but 
decidedly lower than the other trigonid cusps; on mz and mz it is rather 
closely connate with the metaconid, but always recognizable. M3 is about 
as long as me but barely two thirds as wide; its hypoconulid is moderately 
wide and entoconid semi-distinct. 
Comparison with Trogolemur. Tetonius has the same dental formula 
and the front tooth enlarged; nevertheless the detailed comparison of the 
lower teeth does not indicate close affinity. In Trogolemur the root of the 
front tooth reaches far under the molars, the premolars are not enlarged or 
crowded, the last molar is unreduced, and the paraconid, although internal, 
is not connate with the metaconid. -The molars are moderately wide, but 
the outer cusps are marginal, and the outer cingula are very prominent. 
It has much resemblance to the Tarsiidee gen- 
erally but no special resemblance to Tetonius. 
ZAR 
ae ane, \N NS 
Tetonius ambiguus sp. nov. 
Type, No. 15072, lower jaw with p;-m. and 
roots of front teeth, from the lower Gray Bull beds 
in the Bighorn basin, Wyoming. 
Specific characters: Molars of less width than in 
I’. homunculus, third premolar relatively small, 
canine proportionately large, jaw of less depth an- 
teriorly. 
_ The type of this species gives some indica- 
tions of the character of the enlarged front 
tooth. ‘The root is compressed oval, flattened 
Ne ae on the inner side smooth and uniform, indi- 
os cating probably a crown somewhat like that 
lower jaw, inner, outer ana of Cynodontomys, but set rather more vertically. 
crown views. ‘Type specimen, Measurements: Ps-mo = 7.5 mm., approx!- 
Gray Bull beds, Bighorn basin, ‘ 
Wyoming. mately the same as in 7. homunculus. 
