257 



In the genus Canis, as it is at present constituted, there 

 are two main types — the true wolves and the jackalls. These 

 two main types differ from all the other animals, formerly 

 included in the genus, in two intrinsic anatomical features : 



(1) the pupil of the eye is circular when contracted, and 



(2) in the skull, the supra-orbital region and processes are 

 inflated and convex. In these features the true members of 

 the restricted genus Canis (which is practically the Thooid 

 or Lupine series of Huxley) differ from the Alopecoids or 

 Vulpine series, which have the pupil of the eye elliptical, 

 and the supra-orbital region and process uninflated and 

 concave. 



All dogs, domestic or feral, conform to the first type and 

 therefore belong to the restricted srenus Canis or to the 

 Thooids of Huxley. 



Within the restricted genus Canis, the members have a 

 full cynoid dentition, and in this they differ from the wild 

 dogs of south-eastern Asia (the most probable immigrants in 

 a "walk overland" colonization) which possess a dentition 

 reduced by the loss of the last lower molar, and are separated 

 into the genus (J //no. All domestic and feral dogs possess 

 the full dentition, and therefore are not to be considered as 

 descendants of the wild dogs of south-eastern Asia. The 

 true wolves of the northern parts of the Old and New Worlds, 

 and the jackals of southern Europe, Asia, and Africa, are, 

 therefore, left as the possible progenitors of the domestic and 

 feral races of dogs. The northern wolves differ from the 

 jackals in (among other things) the form of , their first upper 

 molar tooth. In the jackals this tooth has a platform — the 

 cingulum — running around the outer (labial) side of the 

 crown ; in the wolves the platform is reduced or wanting in 

 the middle of its length. This condition of reduction of the 

 cingulum must be regarded as a specialization in the northern 

 wolves, since a complete cingulum is present in Alopex, 

 V ulpes, and other Cynoids. 



What is the condition of the cingulum of the first upper 

 molar tooth in the feral or domesticated dog ? — a Cynoid 

 animal which has the full canine dentition, a circular pupil, 

 and an inflated and convex supra-orbital process. Is 

 the cingulum of the generalized Cynoid type, or is it the 

 specialized and reduced type seen only in the true northern 

 wolves ? In every breed of domestic dog that has been 

 examined, the specialized wolf tooth, and not the primitive 

 jackal tooth, has been present. Mr. Gerrit Miller, of the 

 United States National Museum, has given especial attention 

 to this point and has declared the northern wolf origin of 

 all races of domestic dogs (see Catalogue of the Mammals of 



