754 



THE THEORY OF TRANSFORMATIONS 



[CH. 



to points where our rectangular co-ordinates intersect particular 

 bones or other recognisable features in our typical crocodile, we 

 shall easily discover that the lines joining these points in Noto- 

 suchus fall into such a co-ordinate network as that which is 

 represented in Fig. 383, c. To all intents and purposes, then, this 

 not very complex system, representing one harmonious " deforma- 

 tion," accounts for all the differences between the two figures, 

 and is sufficient to enable one at any time to reconstruct a detailed 

 drawing, bone for bone, of the skull of Notosuchus from the model 

 furnished by the common crocodile. 



The many diverse forms of Dinosaurian reptiles, all of which 

 manifest a strong family likeness underlying much superficial 



Fig. 384. Pelvis of (A) Stegosaurus ; (B) Camptosavrus. 



diversity, furnish us with plentiful material for comparison by 

 the method of transformations. As an instance, I have figured 

 the pelvic bones of Stegosaurus and of Camptosaurus (Fig. 384, 

 a, h) to show that, when the former is taken as our Cartesian 

 type, a slight curvature and an approximately logarithmic 

 extension of the x-axis brings us easily to the configuration of 

 the other. In the original specimen of Camptosaurus described 

 by Marsh*, the anterior portion of the iliac bone is missing; and 

 in Marsh's restoration this part of the bone is drawn as though 

 it came somewhat abruptly to a sharp point. In my figure I 



* Dinosaurs of North America, pi. lxxxi, etc. 1896. 



