98 Mr. E. D. Cope on the 



species referred to by European palaeontologists under the 

 name of Cynodictis, Pomel, appear to me to be undistinguish- 

 able 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 American "White-River 

 beds which I have referred to Canis. Helocyon, Aym., may 

 be distinct, but may not belong to the Canidse. 



The dentition of many of the recent species of Canis differs 

 in very slight characters. The following may be detected in 

 an examination 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. 1 composed of two low tubercles. C.familiaris. 

 Vars. molossus, terrarius, grains. 

 Last superior tubercular narrower, transverse ; inner cin- 

 gulum very distinct. 



Inner crest of tub. M. la ridge higher anteriorly C. lupus. 



Inner crest of tub. M. 1 with two sharp cusps C. latrans. 



It is worthy of note that the wide oval form of the second 

 superior molar of the Canis jamiliaris exists equally in the 

 extreme races or species, the greyhound and bulldog, as I 

 observed by examination of several crania of each ; this has 

 also been shown by De Blainvillc ; it is also seen in the 

 terrier and in various other races : but in some St. -Bernard 

 crania in the Museum of the Academy of Natural Sciences 

 this tooth is more elongate, and in some of the specimens of 

 Canis hqms 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 interrupted by 

 a deep vertical excavation. This is not seen in the St. Ber- 

 nard, the bulldog, greyhound, and other races, nor in any of 

 the feral or extinct species of the genus examined. It ap- 

 pears to be associated with an increased size of the brain, and 

 to be an adaptation to the vermis of the cerebellum. The 

 expansion of the brain is also indicated by the protuberance 

 of the frontal region, and the wide separation of the temporal 

 fossee by a smooth space on each side of the sagittal suture. 

 This space does not exist in the greyhound ; but a narrow one 

 is found in the bulldog. These characters are important on 

 various grounds, but are here mentioned in reference to the 

 species of Synagodus and Dysodus, where they reappear. 



