238 On the Extinct Dogs of North America, [ March, . 
torial, in place of a double‘row of tubercles surrounding a basin, 
When well developed these characters present a broad contrast, 
but indications of transitional forms are not wanting. Thus, in — 
some extinct Canes the internal crest of the heel is less elevated 
than the external, which is the homologue of the single crestof 
Fic. 2 f F 
John Day epoch of Oregon; 2. Amphicyon hartshornianus Cope, superi 
rigat afs ; from White River epoch of Colorado. Both figures one-half natural 
riginal. : 
wal aa viewed om won elated Saal Foon Reale 
Geol. Survey Terrs., Vol. 1v. ; 
Temnocyon, and in some specimens of TZemunocyon coryphars : 
there is a cingulum on the inner side of the median keel, which 
represents the internal crest of Canis. Secondly, the epitrochlet 
foramen of the humerus, a character common to all of our 40 
Miocene Canide yet known. nae 
The keel of the sectorial, which defines this genus, is 5! 
repetition on that tooth of the keel which belongs to the 
rior premolar teeth of many Carnivora. I find resemblances 
such Eocene forms as Mesonyx and Palzonyctis. Among 
Canidz it is apparently known only in the genus Icticyo™ 
very rare in other groups. The Cynodictis crassirostris 
from the French Phosphorites, strongly resembles the § 
* 
Temnoecyon in generic characters, and the Amphicyon 
also French, may turn out to belong to this genus. 
