Zoological Society. 379 



Bovverbaiik, Esq., F.R.S. This indefatigable collector had the good 

 fortune to receive in 1845, from the Kentish Chalk, the characteristic 

 jaws and teeth, with part of the scapular arch and a few other bones, 

 of a well-marked species of Pterodactyle, and the discovery was briefly 

 recorded in the ' Quarterly Journal of the Geological Society of Lon- 

 don,' and in the ' Proceedings ' of the Society for May 14, 184$, with 

 an illustrative plate (pi. 1). 



Mr. Bowei-bank concludes his notice by referring to a large fossil 

 wing-bone from the chalk, previously described and figured by me in 

 the ' Geological Transactions,' and remarks that, " if it should prove 

 to belong to a Pterodactyle, the probable expansion of the wings 

 would reach to at least eight or nine feet. Under these circum- 

 stances," he says, '' I propose that the species described above shall 

 be designated Ptei'odactylus yiganteusJ'^ (lac. cit. p. 8.) Subsequent 

 discoveries and observations have inclined the balance of probability in 

 favour of the Pterodactylian nature of the fossils to which Mr. Bower- 

 bank refers, but have shown them to belong to distinct species. 



These fossils are not, indeed, amongst the characteristic parts of 

 the flying reptile : one of them is the shaft of a long bone exhibiting 

 those peculiarities of structure which are common to birds and ptero- 

 dactyles ; the other shows an articular extremity, which, in our pre- 

 sent ignorance of those of the difl*erent bones of the Pterodactyle, has 

 its nearest analogue in the distal trochlea of the bird's tibia. These 

 two specimens, which are figured in the sixth volume of the Second 

 Series of the 'Transactions of the Geological Society,' 1840, pi. 39. 

 figs. 1 & 2, were transmitted to me by the Earl of Enniskillen and 

 Dr. Buckland, as being *'the bones of a bird" (p. 411), and my com- 

 parisons of them were limited to that class. 



The idea of their possibly belonging to a Pterodactyle did occur to 

 me, but it was dispelled by the following considerations. The act of 

 flight — the most energetic mode of locomotion — demands a special 

 modification of the Vertebrate organization, in that subkingdom, for 

 its exertion. But in the class Aves, in which every system is more or 

 less adapted and co-adjusted for this end, the laws of gravitation seem 

 to forbid the successful exercise of the volant powers in species beyond 

 a certain bulk ; and when this exceeds that of the Condor or Albatros, 

 as, for example, in the Cassowary, the Emeu, or the Ostrich, although 

 the organization is essentially that of the Vertebrate animal modified 

 for flight, flight is impossible ; and its immediate instruments, to the 

 exercise of which all the rest of the system is more or less subordi- 

 nated, are checked in their development ; and, being unfitted for 

 flight, they are not modified for any other use. There is not, per- 

 haps, a more anomalous or suggestive phsenomenon in nature than 

 a bird which cannot fly ! A small section of the Mammalia is modi- 

 fied for flight ; but the plan of the organization of that warm-blooded 

 class being less directly adapted for flight than that of birds, the 

 weight and bulk of the body which may be raised and transported 

 through the air are restricted to a lower range, and the largest frugi- 

 vorous Bat {Pteropus) does not exceed the Raven in size. The Rep- 

 tilian modification of the Vertebrate type would seem to be still less 



