ON ANIMALS BETWEEN BIRDS AND REPTILES. 
241 
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 re- 
spects than any now living, once existed. Bones of birds have 
been obtained from rocks of very various 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 or- 
nitholites which have been discovered in the Cambridge green- 
sand, 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 seabottom 
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, Herman von Meyer. 
Von Meyer named the unknown bird to which this feather 
belonged Archceopteryx lithographica, and in the same year, 
the independent discovery by Dr. Haberlein of the precious skele- 
ton of the ArchcBopteryx itself, which now adorns the British 
Museum,* demonstrated the chief characters of the very early 
bird thus named. 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. Some palaeon- 
tologists ma}" be forced b}^ a sense of consistency to declare that 
the class of birds was created in the sole person of Archceop- 
teryx during the deposition of the Solenhofen slates ; that they 
disappeared during the Wealden, to be re-created in the Oreen- 
sand ; and that they vanished once more during the Cretaceous 
epoch and were regenerated in the Tertiaries ; but I incline 
to the hypothesis that many birds beside Archceopteryx 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 Archceopteryx 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 reptile 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 
* The fossil has been described by Professor Owen in the Philosophical 
Transactions ” for 1863. 
