0. C. Marsh—New Tertiary Mammals. 221 
of the tooth. The two anterior cusps are connected by an out- 
ward curving basal ridge. A similar ridge passes from the 
outer posterior cone inward, but does not reach the opposite 
cusp. This upper molar, which is apparently the penultimate, 
measures 2-4™™* in antero-posterior diameter, and 2°1™™ in trans- 
verse diameter. ‘he known remains of the present species were 
found, last autumn, near Henry’s Fork, by Mr. H. D. Ziegler 
and Mr. A. B. Mason, of the Yale party. 
Apatemys bellus, gen. et sp. NOv. 
specimen is a portion of a large rodent-like incisor. The molar 
Transverse diameter of incisor,......-+-++++eee eee eete 
This unique specimen was found, last September, near Henry's 
Fork, by Mr. G. G. Lobdell, Jr. 
Apatemys bellulus, sp. nov. 
Another diminutive mammal, apparently of the same genus, 
but somewhat smaller than the species last described, is we 
> sissy by a lower jaw with the last three molars perfect. 
he penultimate molar agrees in the composition of its crown 
With that of A. Bellus, In the last lower molar, the outer border 
of the posterior cavity forms a slightly eurved longitudinal 
hich termina 
nidge, whic es in asmall tubercle. The molar teet 
are narrow, and the jaw compressed. The cavity for the incisor 
extends below all the lower molars. 
ts. 
Space oceupied by last three lower molars,... +--+ +++ +++ : = 
Antero-posterior diameter of last lower molar,..-+-+-+++++ 21 
Transverse diameter, ....---+s+-sesseeereeccctrerettet 16 
Antero-posterior diameter of penultimate lower molar,... +2" 
Transverse diameter, ..-. ++++++++ eonogeaney See acl 
