NO. 2014. ON A PLEISTOCENE CAVE DEPOSIT— GIDLEY. 101 



siderable angle; the body, or column, of the protocoid is full and 

 rounded, and the metacoid is greatly reduced, appearing in the living 

 species as a small tubercle on the inner posterior angle of the proto- 

 coid near its base (see fig. 4). Similar and fully as important 

 diflFerences are observed in the upper carnassial. The character of 

 the premolars have been stated above, page 98. 



The constancy of these characters seems to mark the wolves and 

 dogs as closely related members of a natural group, and tends to 

 support the behef held by many, and recently especially expressed 

 by Miller,^ that all the domestic breeds of dogs were originally derived 

 from some species of true wolf, and not from the jackal as has been 

 held by some other authorities. 



The subgeneric distinction of the coyotes {Lyciscus) is well sub- 

 stantiated by their tooth characters (see figs. 6, 6a). The teeth in 

 this group are all relatively narrower and less robust than in the 

 wolves, while the carnassial has more the general proportions of 

 those of the j ackal or fox (see figs. 7, 8) . Thus the heel is less reduced, 

 with the two principal cusps more trenchant and more nearly sub- 

 equal; the metaconid is more prominent; the paraconid shorter; 

 and the bodies or columns of the paraconid and protoconid are less 

 full and rounded, leaving the cutting blades of the trigonid much 

 sharper. The p^ has two posterior tubercles and a posterior basal 

 cingulum, and p2 is usually simple. 



Both p2 and p^ are usually simple in the jackals while the crowns 

 of all the premolars are relatively higher and shorter than are those 

 of the coyotes. 



The foxes differ from the other canids in having relatively lower 

 crowned, smaller carnassials as well as in the greater relative length 

 of the canine, as pointed out by Miller.- 



In Cuon and Lycaon the lower carnassials have a completely 

 single-cusped, trenchant heel, which distinguishes them from all the 

 other living canids. There are differences likewise in the upper 

 carnassials and other teeth, especially the molars, which separate 

 this group from Canis and seem to ally it to some of the extinct 

 forms of the late Ohgocene, of the Temnocyon, or Hyxnocyon type. 



Some of the characters mentioned above have been recognized 

 and used by various investigators, but others of seemingly equal 

 importance seem to have been overlooked. 



Herewith is a fist of the principal characters of the lower teeth 

 which seem to be diagnostic for some of the groups of living canids.* 

 Canis armhrusteri is also included. 



' Catalogue of Mammals of Western Europe, 1912, p. 313. 

 2 Idem, p. 326. 



* This is not a complete classification and is onl}' given to show some of the more important tooth char- 

 acters, especially of the carnassials. The South American fox-like dogs are not included here. 



