448 
III. 
Ly. 
Bulletin American Museum of Natural History. [Vol. XXXIV, 
Paraconids distinct, median, metaconids postero-internal to protoconids, no 
metastylids. Incisors small, canine of moderate size. Jaw short and deep 
anteriorly, front teeth vertical. Premolars crowded, ps-s enlarged, trenchant 
with quadrate base, no deuteroconids.....................-.4- Uintanius. 
Paraconids distinct, median, metaconids opposite protoconids, metastylids 
distinct. ‘I'wo minute incisors, canine small, jaw short and deep anteriorly, 
front teeth vertical. Premolars crowded, small, deuteroconid distinct on ps3_4. 
1. Melars broader, heel-of ms DicUspId: 4.05% 5 aa et ne oe W ashakius. 
2, Wiolars marvower, heel of Mig ginger. ce 5 ve as eee vw Shoshonius. 
-Paraconids internal, more or less connate with metaconids; metaconids opposite 
or somewhat posterior to protoconids, no metastylids. Molar cusps less. 
marginal than in the preceding groups. Jaw short and deep anteriorly. Pre- 
molars robust, no deuteroconids. 
1. Ms; unreduced, paraconids vestigial except on m; 
a. ‘Two minute incisors, canine small. p2 absent, ps smaller than mj. 
: Anaptomorphus. 
De AMUCIION Geet IMmnOW ws hak ba ca cee co es Euryacodon. 
2. Ms; reduced, paraconids more distinct, three premolars. 
a. Canine and one incisor moderately enlarged, posterior premolars much 
PIC he re er ala auc eat utara Vet de oo Sa, Absarokius. 
b. No incisors, canine much enlarged, posterior premolars somewhat 
OO ee a ee katy Ghik cu cas Tetons. 
The geological range of the Eocene genera is as follows: 
Omomys 
Hemiacodon 
Uintanius 
Shoshonius - 
Gray Bull Lysite Lost Cabin | L’r Bridger |Up’r Bridger 
Washakius | ? * 
* 
Anaptomorphus 
Euryacodon 
Absarokius “ 
Tetonius 
Omomys Leidy 1869. 
7? 3.8. 
Y e é se Wind ° e e . 
Generic characters: Dentition 2133: Yaw long.and slender, incisors semi- 
procumbent, the first.somewhat enlarged, the second small. Canine larger than po, 
somewhat larger than ij. Premolars with triangular bases, not crowded, pz very 
small, ps simple, high crowns, ps smaller than m1, deuteroconid distinct. ‘“Molars 
_ with strong well separated paraconid, median or submedian in position; crowns low, 
cusps submarginal, enamel smooth. M3 unreduced. Upper molars trigonal, 
