THE LAWS OF VARIABILITY. 55 



ColumbidcB for a beak like that of the English carrier, or 

 that of the short-faced tumbler, or barb ; for reversed 

 feathers like those of the Jacobin ; for a crop like that of 

 the pouter; for tail-feathers like those of the fantail. 

 Hence it must be assumed not only that half-civilized 

 man succeeded in thoroughly domesticating several spe- 

 cies, but that he intentionally or by chance picked out 

 extraordinarily abnormal species ; and, further, that these 

 very species have since all become extinct or unknown. 

 So many strange contingencies are improbable in the 

 highest degree. 



OBIGIX OF THE DOG. 



Animals and The first and chief point of interest in this 

 Dom" tica- Cr chapter is, whether the numerous domesticated 

 tion, vol. i, varieties of the dog have descended from a sin- 

 gle wild species, or from several. Some au- 

 thors believe that all have descended from the wolf, or 

 from the jackal, or from an unknown and extinct species. 

 Others again believe, and this of late has been the favor- 

 ite tenet, that they have descended from several species, 

 extinct and recent, more or less commingled together. 

 We shall probably never be able to ascertain their origin 

 with certainty. Paleontology does not throw much light 

 on the question, owing, on the one hand, to the close 

 similarity of the skulls of extinct as well as living wolves 

 and jackals, and owing, on the other hand, to the great 

 dissimilarity of the skulls of the several breeds of the 

 domestic dogs. It seems, however, that remains have 

 been found in the later tertiary deposits more like those 

 of a large dog than of a wolf, which favors the belief of 

 De Blainville that our dogs are the descendants of a 

 single extinct species. On the other hand, some authors 

 50 so far as to assert that every chief domestic breed must 



