1915.| Matthew and Granger, Lower Eocene Wasatch and Wind River Faunas. 3.49 
in the proper position for the development of the metaloph. There is, how- 
ever, the important point that in the numerous specimens now available from 
several horizons no marked tendency toward the formation of a metaloph 
is shown. The metaconule is sometimes isolated, often connected with the 
protocone, and in some cases connected with both the protocone and hypo- 
cone forming with the protoconule two Vs, the posterior one opening toward 
the palate, the anterior one toward the center of the tooth. In only one 
specimen is the metaconule found connected with the hypocone and sepa- 
rated from the protocone by a deep valley as in Perissodactyla, and this 
individual happens to be from the lowest horizon of the genus and appar- 
ently represents merely an isolated example of deviation from the ordinary 
Trt Fs, E. superstes . 
NO. (Type, Lost Cabin beds, Wind 
River basin, Wyo.) 
NC\RS, 
as 
Noa. 2334, A./4. 
EK. osbornianus 
(Topotype, Gray Bull beds, Big- 
horn basin, Wyo.) 
see tO Pine 
ie if 
0./617F4,A. (4. 
EF. ralstonensis 
(Type, Clark. Fork beds, Clark 
Fork basin, Wyo.) 
EH. parvus 
Kl > (Type, Clark Fork beds, Clark 
Ne. 16980, A.A Fork basin, Wyo.) 
Fig. 12. Lower teeth, crown views, of the species of Ectocion. 
condition, rather than any distinct phylum. The genus is of interest in 
this connection as presenting the type of upper molar from which the 
Perissodactyl molars might have been derived. | 
Additional Characters of Ectocion. Besides the characters given in the: 
Key to Genera there are certain other features which separate this genus 
from Phenacodus. There is usually a metaconule on the pt. The m* seldom 
has a hypocone and is a triangular tooth; in Phenacodus the hypocone is 
usually present, although smaller than the protocone. In Ectocion the hypo- 
conulid 6f the lower molars is usually crowded inward toward the entoconid, 
while in Phenacodus this cusp is in the center of the tooth. In KEctocion 
there is a ridge descending anteriorly from the protoconid and passing across 
to the inner side of the tooth; in Phenacodus the ridge is joined in the center 
