XVII] THE COMPARISON OF RELATED FORMS 773 



strictly speaking, continuous, and that neither of our two apes 

 lies precisely on the same direct line or sequence of deforma- 

 tion by which we may hypothetically connect the other with 

 man. 



As a final illustration I have drawn the outline of a dog's 

 skull (Fig. 408), and inscribed it in a network comparable with 

 the Cartesian network of the human skull in Fig. 404. Here we 

 attempt to bridge over a wider gulf than we have crossed in any 

 of our former comparisons. But, nevertheless, it is obvious that 

 our method still holds good, in spite of the fact that there are 

 various specific differences, such as the open or closed orbit, etc., 

 which have to be separately described and accounted for. We 

 see that the chief essential differences in plan between the dog's 

 skull and the man's lie in the fact that, relatively speaking, the 



Fig. 408. Skull of dog, compared with the human skull of Fig. 404. 



former tapers away in front, a triangular taking the place of a 

 rectangular conformation ; secondly, that, coincident with the 

 tapering off, there is a progressive elongation, or pulling out, of 

 the whole forepart of the skull ; and lastly, as a minor difference, 

 that the straight vertical ordinates of the human skull become 

 curved, with their convexity directed forwards, in the dog. While 

 the net result is that in the dog, just as in the chimpanzee, the 

 brain-pan is smaller and the jaws are larger than in man, it is 

 now conspicuously evident that the co-ordinate network of the 

 ape is by no means intermediate between those which fit the other 

 two. The mode of deformation is on different lines; and, while 

 it may be correct to say that the chimpanzee and the baboon are 

 more brute-like, it would be by no means accurate to assert that 

 they are more dog-like, than man. 



