198 MOSTLY MAMMALS 
trace the ancestry. A German writer, the late Prof. L. 
Fitzinger, considered that domesticated dogs might be 
divided into seven well-marked groups, which included 
close upon a couple of hundred of more or less well-marked 
breeds and varieties. Other authorities are, however, of 
opinion that the number of main groups might be reduced 
to half a dozen, these including wolf-like dogs, such as the 
Eskimo breed, the various kinds of greyhounds, spaniels, 
hounds, mastiffs, and lastly terriers. , 
All who have written on the subject are in accord in 
regarding all domesticated dogs, with the exception of the 
Australian dingo, as constituting but a single species—the 
Canis familiaris of Linnaeus. But if it be true, as seems 
probably the case, that domesticated dogs trace their 
ancestry to more than a single wild species, it will be 
obvious that Canis familiaris cannot in any sense be re- 
garded as equivalent to an ordinary wild species ; and that, 
properly speaking, if this were possible, the various true 
breeds ought to be affiliated to the wild species from which 
they are respectively derived. Still, for practical purposes, 
the ordinary classification may be accepted, if it be remem- 
bered that Canzs familiaris, like Felis domestica, is in all 
probability a “convergent” species. 
By naturalists all the members of the dog tribe are in- 
cluded in the great family Canidae, which thus embraces 
wolves, jackals, foxes, wild dogs, the African hunting-dog, 
the long-eared fox of the Cape, and the bush-dog of Guiana. 
Somewhat different views are entertained as to how many 
of these should be included in the typical genus Canis, but 
this is a matter which needs no consideration here, and we 
may accordingly proceed to eliminate from the list those 
groups which have certainly no claim to be on the ances- 
tral line of the domesticated breeds. 
