11 
normal variations. These are, however, not so frequent as to 
invalidate the classification to which they form the exceptions. 
The Canidx appeared in the Upper Eocene period, and the 
genus Canis was well represented by species in the lowest Mio- 
cene in Europe and the United States. The other genera are 
represented by fewer species, and many of them are extinct. The 
foxes (Vulpes) are the most numerous of them, and but few extinct 
species of them are known. America presents us with the greatest 
variety of genera, as Enhydrocyon, Temnocyon, and Palxocyon 
extinct, and Jcticyon, extinct and recent. Speothus, extinct in 
America, still exists in Asia. 
The most complete catalogue of the species Canidz is that of 
Dr. Gray. In his work the author brings together observations 
of various naturalists, and adds a number of his own. He admits 
a large number of generic divisions, but many of these, like those 
of his Felidx, are simply founded on specific characters. A few 
good genera, however, exist, and a synopsis of their characters is 
given below. The genus Megalotis is here excluded from the 
Canide on account of the unspecialized character of the superior 
sectorial tooth, as is done by Dr. Gray :— 
I. True molars 3. 
Premolars 4; inferior sectorial with internal tubercle. 
Amphicyon. 
II. True molars 3. 
Premolars 4; inferior sectorial with internal tubercle. 
Thous. 
III. True molars 3. 
o. Premolars 4. 
Bg. Inferior sectorial without internal tubercle. 
Heel of sectorial cutting. Paleocyon. 
gs. Inferior sectorial with internal tubercle. 
y- Four toes in the manus; ; 
A sagittal crest. Lycaon. 
yy: Five toes in the manus. 
8. Heel of sectorial simply cutting. 
A median sagittal crest (? toes). Temnocyon 
85. Heel of sectorial concave, with raised borders. 
Pupil round; temporal fossa with simple superior border. 
Canis. 
