supposed to be furnished with Feathers. 265 
lumbar vertebrze are free and uncovered, and the lateral bones 
of the pelvis are but slightly developed. ‘The difference in the 
structure of the tail is equally striking. All birds, without ex- 
ception, have a very short and powerful tail, composed of from 
five to eight, and only in a few cases of nine or ten vertebra, 
which bear strong processes, and of which the last is always 
peculiarly formed, and also, with but few exceptions, the largest. 
The opposite of all this is exhibited by the tail of the fossil. In 
this the tail is extraordinarily long, and consists of about twenty 
vertebrz, which are all elongated, slender, and without processes, 
and the last of them is the smallest. Such a condition of things 
is completely in contradiction to the bird-type, but, on the other 
hand, agrees very closely with that of Rhamphorhynchus, in 
which, moreover, radiating processes issue from the caudal ver- 
tebre, although these are not feather-like, but appear to be 
simple cartilaginous fibres. 
I have thus detailed those data which have become accessible 
to me, in order to endeavour to answer the question whether 
this fossil is to be referred to the class of birds or to that of rep- 
tiles. The difficulty of doing this with certainty is indeed greatly 
increased by the circumstance that the skeleton is entirely desti- 
tute of certain extremely important parts, of which the skull and 
the hand may be particularly adduced ; nevertheless an attempt 
at some interpretation must be ventured upon. In the first 
place, I consider the great uniformity, especially in the structure 
of the skeleton, presented by the type of birds, which, in com- 
parison with that of the other classes of Vertebrata, only admits 
of inconsiderable variations ; whilst amongst the reptiles—and as 
in the present case we have to do only with the Saurian order, 
in these, the most remarkable differences occur within the boun- 
daries of the order, as may be seen from living and still more 
from extinct species of Sauria. For this reason, therefore, a 
reptile with the simple tarsal bone of a bird, and with epi- 
dermic structures presenting a deceptive resemblance to birds’ 
feathers, is far more comprehensible to me than a bird with the 
pelvis and vertebral column (especially the long slender series 
of caudal vertebre) of a long-tailed Pterodactyle, and with a 
perfectly different mode of attachment of the feathers. To this 
we may add that the identity of these epidermic structures with © 
true birds’ feathers is by no means proved ; they might still only 
be peculiar adornments. Even amongst insects we find peculiar 
structures, to a certain extent reminding us of feathers; why, 
therefore, not also, and in a higher stage of development, among 
reptiles? If nothing of the kind has yet been found in the latter 
class, we have already been accustomed in paleontology to meet, 
in recent discoveries, with previously unknown peculiarities in 
