23 



having regarded the specimens " as belonging to an extinct species 

 of Albatros." My reference of the bones even to the longipennate 

 tribe of natatorial birds is stated hypothetically and with due caution : 

 " On the supposition that this fragment of bone is the shaft of the 

 humerus, its length and comparative straightness would prove it to 

 have belonged to one of the longipennate natatorial birds equalling in 

 size the Albatros." {loc. cit. p. 411.) 



Since the discovery has been made of the manifestly characteristic 

 parts of the genus Pterodactylus in the Burham chalk-pit, it has been 

 objected that the bones first discovered there, and described by me 

 as resembling birds of flight, " are so extremely thin, as to render it 

 most improbable that they could ever have sustained such an instru- 

 ment of flight as the powerful wing of the Albatros, or of any other 

 bird : their tenuity is in fact such," says the ex post facto Objector, 

 " as to pomt out their adaptation to support an expanded membrane, 

 but not pinions *." 



The reply to this assertion need only be a simple reference to na- 

 ture : sections of the wing-bones of birds may be seen in the Museum 

 of the Royal College of Surgeons, and have been exposed to view, 

 since the discovery of their structure by the Founder of that Collec- 

 tion, in every Museum of Comparative Anatomy worthy to be so 

 called. 



To expose the gratuitous character of the objection above cited, I 

 have placed on the table a section of the very bone that directly sus- 

 tains the large quill-feathers in the Pelican ; its parietes are only half 

 as thin as those of the antibrachial bone of the great Pterodactyle 

 which is figured in my ' History of British Fossil Reptiles,' pi. 4, and 

 is not thicker than those of the bone figured in the Geological Trans- 

 actions, 1840, above cited. 



Hunter, who had obtained some of the long bones with thin 

 walls and a wide cavity from the Stonesfield slate, has entered them 

 in his MS. Catalogue of Fossils as the "Bones of Birds," and per- 

 haps no practical anatomist had had greater experience in the degree 

 of tenuity presented by the compact walls of the large air-ca^dties of 

 the bones in that class. Of all the modifications of the dermal system 

 for combining extent of surface with lightness of material, the ex- 

 panded feather has been generally deemed the consummation. Well 

 might the eloquent Paley exclaim, "Every feather is a mechanical 

 wonder : their disposition all inclined backwards, the down about the 

 stem, the overlapping of their tips, their different configuration in dif- 

 ferent parts, not to mention the variety of their colours, constitute a 

 vestment for the body so beautifid and so appropriate to the life 

 which the animal is to lead, as that, I think, we should have had 

 no conception of anything equally perfect, if we had never seen it, or 

 can imagine anything more so." It was reserved for the author of 

 the ' Wonders of Geology ' to prefer the leathern wing of the Bat and 

 Pterodactyle as the lighter form, and to discover that such a structure 

 as is displayed in the bone described and figured in the ' Geol. Trans.' 



* Mantell, ' Wonders of Geology,' 1848, vol. i. p. 441. 



