84: THE GENESIS OF SPECIES. [CHAP. 



evolutionists that those ancient flying reptiles, the ptero- 

 dactyls, or forms allied 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 " Hunterian Course " 

 for 1867, when attention was called to the existence in Di- 

 morphodon macronyx of even that small process which in 

 birds gives attachment to the upper end of the merry- 

 thought. Also Mr. Seeley B 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, 6 as also by Prof. Cope in the United 

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

 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 difficulty presents itself as 

 to the explanation of the three following relationships : 

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



5 See "Ann. and Mag. of Nat. Hist." for August, 1870, p. 140. 



6 See " Proceedings of the Koyal Institution," vol. v., part iv,, p. 278 : 

 Report of a Lecture delivered February 7, 1868. Also " Quarterly Jour- 

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

 Anatomy and Taxonomy of the Dinosauria." 



