17 
From the Truckee beds of the White River formation in Oregon. 
Canis, Linn. : 
The names proposed by Smith, Gray, and others, and which 
must be regarded as synonyms of Canis, are Lupus, Dieba, Si- 
menia, Chrysocyon, and Lycalopex. Many of the species, referred 
to by European paleontologists under the name of Cynodictis, 
Pomel, appear to me to be undistinguishable from Canis. Through 
the great kindness of M. Filhol, I possess specimens of the jaws 
of several of these species. A mandible with nearly complete 
dentition of the Cynodon velaunum of Aymard, agrees very 
nearly with the jaws of some of the smaller species from the Ame- 
rican White River beds, which I have referred to Canis. Helocyon, 
Aym. may be distinct, but may not belong to the Canide. 
The dentition of many of the recent species of Canzs differs in 
very slight characters. The following may be detected in an ex- 
amination of the superior molars of the three larger species most 
accessible in the United States. 
Last superior tubercular short, wide; inner cingulum and crest 
nearly confounded. 
Inner crest of tub. m. I. composed of two low tubercles. 
; C. familiaris. 
Vars. molossus, terrarius, graius. 
Last superior tubercular narrower, transverse ; inner cingulum 
very distinct. 
Inner crest of tub. M. I., a ridge higher anteriorly. C. lupus. 
Inner crest of tub. M. I. with two sharp cusps. C. latrans. 
It is worthy of note that the wide oval form of the second supe- 
rior molar of the Canis familiaris, exists equally in the extreme — 
races or species, the grayhound and bulldog, as I observe by ex- 
amination of several crania of each. This has also been shown by 
De Blainville. It is also seen in the terrier, and in various other 
races. But in some Saint Bernard crania in the Museum of the 
Academy of Natural Sciences, this tooth is more elongate; and in 
some of the specimens of Canis lupus from Europe its form is 
quite the same. So this character, as might have been anticipated, 
is not of universal application. Another character is seen in the 
crania of three specimens, which are supposed to belong to Canis 
terrarius. The superior border of the foramen magnum is inter- 
rupted by a deep vertical excavation. This is not seen in the St. 
2 
