12 
Pupil erect ; temporal fossa with simple superior border. 
‘ Vulpes. 
Pupil erect; temporal fossa bounded above by a rib-like 
crest. Urocyon. 
aa. Premolars 3. 
Inferior sectorial with internal tubercle and cutting heel. 
Enhydrocyon. 
Inferior sectorial with internal tubercle, and wide tubercu- 
lar heel. Tomarctus. 
IV. True molars 2. 
a. Premolars 4. 
Inferior sectorial with internal tubercle. Speothus. 
Inferior sectorial without internal tubercle (superior molar 
sometimes one). Synagodus. 
da. Premolars 3. 
Inferior sectorial without internal tubercle (incisors caduc- 
ous). Dysodus. 
V. True molars 4 ; 
Premolars 4; inferior sectorial with internal tubercle. 
Icticyon. 
It is discoverable that the series represented by the above genera 
is a part of the greater line of the digitigrade Carnivora, embrac- 
ing the greater part of it which is less specialized than, or infe- 
rior to, the part covered by the Hyzenide and Felide. Without 
entering into the relations of the Canide with the civets and 
Mustelide, it may be remarked that the genera display a succes- 
sive reduction in the number of premolars and molars from the 
more ancient to modern geologic times. It is interesting to note 
that the genera presenting the greatest reduction in all respects, 
Synagodus and Dysodus, are now only known in a domesticated 
condition. Another reduction is seen in the number of tubercles 
of the inferior sectorial. 
Amphicyon, Lartet. 
This genus is better represented in Europe than in North Ame- 
rica, but two species being certainly known from the latter. No 
recent species. 
Thous, Gray, Dusteyon, Smith (nomen nudum). 
Existing species of South America only. 
