THE ZOOLOGICAL POSITION OF THE DOG. 9 



and ankle of man the " hock " of the dog. Usually, in 

 the dog the innermost toe is rudimentary (dew-claw), 

 though the feet, like other parts of this animal, vary 

 a good deal. 



Variations. — There is scarcely a physical feature in 

 which dogs do not vary, as will be more evident after 

 an examination of the peculiarities of different breeds. 

 Some of these, however, are of scientific interest and 

 worthy of notice in passing. It might almost be said 

 that there is not a bone in the framework of this animal 

 which does not vary in the different breeds of dogs, not 

 to speak of differences in size, coat, carriage, and psychic 

 traits. The shape of the head is not identical in any two 

 breeds — a difference which generally extends to the bones 

 composing it. Correlated with this are differences in the 

 size and shape of the brain. Possibly also, in some cases 

 at all events, variations in the shape, and especially the 

 number, of the teeth are to be referred to modifications 

 in the size and shape of the jaws. The almost entire 

 absence of teeth, as in the Turkish dog, is to be regarded 

 in the light of defective development, as also the lack of 

 hair in the Mexican hairless variety. In large breeds of 

 dogs there seems to be a tendency to the development of 

 a fifth toe, especially behind. The extent to which the 

 feet are webbed — i. e., the toes united by skin — is also 

 variable and characteristic of some breeds. But, in fact, 

 dogs vary in every possible respect, both physical and 

 psychical, as even a moderately careful study of the dif- 

 ferent breeds will show, and this illustrates the remarkable 

 power of animals to vary under domestication. One of 

 the subjects of great interest in the study of this animai 



