From the Tertiary Formation. 48 
: Measurements. 
Length of part of lower jaw containing first molar and ~ 
two premolars, -....-.-.--- 5:1 lines. 
Ad cc 
lob “ 1°6 “ce 
Antero-posterior diameter of last lower premolar,.... 16 “ 
The specimens representing this species at present were 
found by the writer, at Grizzly Buttes, Wyoming. 
Limnotherium tyrannus, gen. et sp. nov. 
A somewhat larger pachyderm, but distantly allied appar- 
ently to the two small species last described, is represented by 
the anterior portions of two ynited lower jaws, with several 
teeth, and a few other fragmentary remains. These specimens 
appear to indicate a genus quite distinct from any hitherto 
known, but additional remains will probably be required to de- 
termine its exact affinities. The teeth of the lower jaws are 
twenty in number, and form an uninterrupted series, which 
may be divided as follows:—Incisors 2-2, canines 1-1, pre- 
molars 44, molars 8-8. The incisors are small, and crowded 
together. The canines are large, nearly round at the base, and 
evidently formed most. efficient weapons. The first and second 
premolars had but a single fang. ‘The two anterior molars 
are in excellent preservation, and have their crowns composed 
Measurements. 
Length of dental series of lower jaw,---------------- 18° lines 
Antero-posterior extent of three molars, . ------------- 75 z 
Transverse extent of four incisors, . - 
ngth of symphysis, _... ._.----- ioe a! 
Depth of lower jaw below last molar, ae IS . 
Depth below last premolar: 22.220 oes Sigs ee 
Antero-posterior extent of first lower molar, ---------- 2°5 zi 
TanSverse diameter of same, . i... ...---. +4: == +54 -<- 2 
The specimens here described were found by the writer near 
Dry Creek, Western Wyoming, in deposits which are probably 
of Upper Eocene age. 
: Limnotherium elegans, sp. nov. 
_. A diminutive mammal is represented in our collections by 
Portions of two lower jaws, with several teeth, which have so 
