84 TlIK GKNESrS OF SPECIES. [Chap. 



evolutionists tliat tliose ancient flying reptiles, the ptero- 

 dactyls, or foriDS iillied to them, were the progenitors of 

 the class of birds ; and certain parts of their structure espe- 

 cially support this view. Allusion is here made to the 

 blade-bone (scapula) and the bone which passes down from 

 the shoulder-joint to the breast-bone (viz., the coracoid). 

 These bones are such remarkable anticipations of the same 

 parts in ordinary (i. e., carinate) birds that it is hardly pos- 

 sible for a Darwinian not to regard the resemblance as due 

 to community of origin. This resemblance was carefully 

 pointed out by Prof. Huxley in his " Ilunterian Course " 

 for 18G7, when attention was called to the existence in Dl- 

 inorphodon inacromjx of even that small process which in 

 birds gives attachment to the upper end of the merry- 

 thought. Also Mr. Seeley * has shown that in pterodac- 

 tyls, as in birds, the optic lobes of the brain were placed 

 low down on each side — " lateral and depressed." Never- 

 theless, the view has been put forward and ably maintained 

 by the same professor,' as also by Prof. Cope in the United 

 States, that the line of descent from reptiles to birds has 

 not been from ordinary reptiles, through pterodactyl-like 

 forms, to ordinary birds, but to the struthious ones from 

 certain extinct reptiles termed Dinosauria ; one of the most 

 familiarly known of which is the Iguanodon of the Weal- 

 den formation. In these Dinosauria we find skeletal char- 

 acters unlike those of ordinary (i. e., carinate) birds, but 

 closely resembling in certain points the osseous structure 

 of the struthious birds. Thus a difliculty presents itself as 

 to the ex[)lanation of the three following relationships: 

 (1) That of the Pterodactyls with carinate birds; (2) that 



* See "Ann. and Mag. of Nat. Ilist." for August, 1870, p. 140. 



® See " Proceeilingd of the lioyul Institution," vol. v., part iv., p. 278 : 

 Report of a Lecture delivered February 7, 1808. Also " (^uirterly Jour- 

 nal of the Geological Society," February, 1870. "Contributions to the 

 Anatomy and Taxonomy of the Dinosauria." 



^^. 



