70 Royal Institution : — 



It is very instructive to note by how mere a chance it is we 

 happen to know that a fossil bird, more reptilian in some respects 

 than any now living, once existed. 



Bones of birds have been obtained from rocks of very varions dates 

 in the Tertiary series without revealing any forms but such as would 

 range themselves among existing families. 



A few years ago the great Mesozoic formations had yielded only 

 the few fragmentary ornitholites which have been discovered in the 

 Cambridge greensand, and which are insufficient for the complete 

 determination of the affinities of the bird to which they belonged. 



However, the very fine calcareous mud of the ancient Oolitic sea- 

 bottom which has now hardened into the famous lithographic slate of 

 Solenhofen, and has preserved innumerable delicate organisms of the 

 existence of which we should otherwise have been, in all probability, 

 totally ignorant, in 1861 revealed the impression of a feather to the 

 famous palaeontologist Hermann von Meyer. Yon Meyer named the 

 unknown bird to which this feather belonged Arcliceopteryoc lithogra- 

 jpTiica ; and in the same year the independent discovery by Dr. Haber- 

 lein of the precious skeleton of the Archceopteryoc itself, which now 

 adorns the British Museum *, demonstrated the chief characters of 

 this very early bird. But it must be remembered that this feather 

 and this imperfect skeleton are the sole remains of birds which have 

 yet been obtained in all that great series of formations known as 

 Wealden and Oolite, which partly lie above, and partly correspond 

 with, the Solenhofen slates. 



Though some palaeontologists may be forced, by a sense of con- 

 sistency, to declare that the class of birds was created in the sole 

 person of Archmopteryx during the deposition of the Solenhofen slates 

 and disappeared during the Wealden, to be recreated in the Green- 

 sand, to vanish once more during the Cretaceous epoch and reappear 

 in the Tertiaries, I incline to the hypothesis that many birds beside 

 Archceopteryai existed throughout all this period of time, and that we 

 know nothing about them, simply because we do not happen to have 

 hit upon those deposits in which their remains are preserved. 



Now, what is this ArchceoiJteryx like ? Unfortunately the skull 

 is lost ; but the leg and foot, the pelvis, the shoulder- girdle, and the 

 feathers, so far as their structure can be made out, are completely 

 those of existing ordinary birds. 



On the other hand, the tail is very long, and more like that of a 

 reptUe than that of a bird in this respect. Two digits of the manus 

 have curved claws, much stronger than those of any existing bird ; 

 and, to all appearance, the metacarpal bones are quite free and 

 disunited. 



Thus it is a matter of fact that, in certain particulars, the oldest 

 known bird does exhibit a closer approximation to reptilian structure 

 than any modem bird. 



Are any fossil reptiles more bird-like than those which now 

 exist ? 



* The fossil lias been described by Professor Owen, in the 'Philosophi- 

 cal Transactions ' for 1863, 



