1846.] 



MANTELL ON WEALDEN BIRDS BONES. 



105 



between it and the fossil. When Professor Owen, in 1835, obligingly 

 offered to institute a rigorous examination of all the bones in my 

 collection that were supposed to be referable to Birds or Pterodac- 

 tyles, his attention was particularly requested to the specimen in 

 question. The result of that examination was given by me in the 

 Memoir on Fossil Birds, above referred to, and to that paper I beg 

 to refer, to avoid unnecessary repetition. It will suffice for my pre- 

 sent purpose to state that Professor Owen deemed my conjecture as 

 to the original individuality of the two portions erroneous, and re- 

 ferred the head of the bone to a humerus, as I had done, but the 

 other extremity he pronounced to be the tarso-metatarsal of a Wader. 

 In Professor Owen's recent communication to the Society, the data 

 on which his present interpretation of that fragment is founded are 

 fairly and perspicuously detailed. Both portions he now admits to 

 belong to but one bone ; and the supposed tarso-metatarsal, which 

 upon such high authority I had announced as affording proof of the 

 existence of birds during the Wealden period, proves to be the lower 

 extremity of a humerus. This humerus, for anatomical reasons which 

 are fully explained in Professor Owen's communication, he now con- 

 siders to be indisputably that of a Pterodactyle, and not of a Bird ; 

 and he also arrives at the conclusion that all the other supposed birds' 

 bones of the Wealden must be referred to flying reptiles ; an opinion 

 which I submit is not based on satisfactory grounds. In the first place, 

 the bone which has given rise to these remarks is imperfect at both ex- 

 tremities. The inferior end, though now rendered somewhat more in- 

 telligible from a few particles of stone having recently been removed, 

 has but a very small part of the articulating surface remaining, and 

 there are no characters by which a correct outline of the original 

 could be restored. The upper part is also imperfect, and if it be 

 assumed to belong to a Pterodactyle, it should, 

 I conceive, have some indications of the pro- 

 minent convex head {a) to fit the socket of the 

 glenoid cavity, as in the humerus of the Pte- 

 rodactylus crassirostris of Goldfuss, of which 

 an outline is annexed ; but no vestige of such 

 a process can be discovered. The utmost 

 therefore that can be predicated as to the fossil 

 is, that it is the humerus of an animal capable 

 of flight; that it possesses characters which 

 bring it in close relation to the corresponding 

 bone of Birds and Pterodactyles, but that the 

 state of the articulating surfaces of the extre- 

 mities is too imperfect to warrant a positive 

 determination as to which order of beings the 

 original belonged. To affirm that this humerus 

 is that of a Pterodactyle appears therefore to 

 me, in the present state of our knowledge, 

 just as likely to lead to error as was the former 

 misinterpretation of the lower extremity of this fossil. In the next 

 place, notwithstanding the accession whicii has been made to paliv- 



Hunierus of Pterodactvk 

 from GoUUuss. 



