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 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 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 paleontologist Hermann von Meyer. Von Meyer named the 
unknown bird to which this feather belonged Archewoptery« lithogra- 
phica ; and in the same year the independent discovery by Dr. Hiiber- 
lein of the precious skeleton of the Archwopteryw 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 paleontologists may be forced, by a sense of con- 
sistency, to declare that the class of birds was created in the sole 
person of Archwopterya 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 
Archeopteryx 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 Archeopteryx 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 
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 modern bird. 
Are any fossil reptiles more bird-like than those which now 
exist ? 
* The fossil has been described by Professor Owen, in the ‘ Philosophi- 
cal Transactions ’ for 1863, 
