1068 THE THEORY OF TRANSFORMATIONS [ch. 



of the bone in harmony with the general coordinate network which 

 is suggested by our comparison of the two entire pelves; and I 

 venture to think that the result is more natural in appearance, and 

 more hkely to be correct than was Marsh's conjectural restoration. 

 It would seem, in fact, that there is an obvious field for the employ- 

 ment of the method of coordinates in this task of reproducing missing 



2 I 



Fig. 529. Shoulder-girdle of Cryptocleidus. a, young; 6, adult. 



portions of a structure to the proper scale and in harmony with 

 related types. To this subject we shall presently return. 



In Fig. 529, a, b, I have drawn the shoulder-girdle of Cryptocleidus, 

 a Plesiosaurian reptile, half-grown in the one case and full-grown 

 in the other. The change of form during growth in this region of 

 the body is very considerable, and its nature is well brought out 



l^ --^,0 



2. 



Fig. 530. Shoulder-girdle of Ichthyosaurus. 



by the two coordinate systems. In Fig. 530 I have drawn the 

 shoulder-girdle of an Ichthyosaur, referring it to Cryptocleidus as 

 a standard of comparison. The interclavicle, which is present in 

 Ichthyosaurus, is minute and hidden in Cryptocleidus] but the 

 numerous other diiferences between the two forms, chief among 

 which is the great elongation in Ichthyosaurus of the two clavicles, 

 are all seen by our diagrams to be part and parcel of one general 

 and systematic deformation. 



