0. C. Marsh—Notice of New Tertiary Mammals. 533 
jaw preserved is massive and deep, and contained six molar 
teeth, all essentially alike, and inserted in deep sockets. They 
all grew from persistent pulps) In form, they are nearly 
cylindrical, with an approach to a quadrate outline in transverse 
section. The outer and inner faces are covered with a thin layer 
of enamel. A portion of a large incisor was found with this 
jaw, and evidently pertains to the same animal. This tooth 
was large, and somewhat curved. Its outer face was coated 
with enamel, marked with transverse lines of growth, and ver- 
tical striae. 
Measurements. 
Extent (approximate) of six lower molars, _.....--.----- 45mm. 
Antero-posterior diameter of third lower molar,. -.----- 11° 
Transverse eanpter Ss a a ee Se ee 12°3 
Width of external layer of enamel, 9. 
Thickness, ipa ak oe Uy ele eget cue eres 2 GES 
Length of inserted portion of upper molar,.-.-----.---- ‘41° 
Depth of pulp cavity, ee 20° 
Width of band of enamel 6n ROE. oo ae 22° 
The only remains of this species now known are from the 
eal Kocene of western Wyoming. They belong to a single 
indi 
vidual, which was about as large as a Capybara. 
Tillotherium latidens, sp. nov. 
Measurements. 
Antero-posterior diameter of last upper molar,_.-.------- tea 
Antero-posterior diameter through outer lobes, -.. . .--- -- 26° 
Antero-posterior diameter through inner cone, 23° 
* This Journal, v, p. 485, June, 1873. 
