Mr. H. Seeley ow the Avian Affinities of Pterodactyles. 325 
of birds, at the meeting of the British Association in Bath. 
And now Prof. Owen, in his ‘Comparative Anatomy,’ elevates 
the Pterodactyles to the rank of the highest group of reptiles 
—thus placing them between the recognized Reptilia and Aves, 
as I had done. 
Under these circumstances I venture to submit an epitome of 
the evidence which led to the conclusion that Pterodactyles are 
a subclass of bird-allies, and have nothing whatever t» unite them 
with the Reptilia—a result which has been chiefly worked out 
from Cambridge specimens, which have been almost invariably 
determined by comparing the articular surfaces of the bones. 
And thus the osteology of the group has been made out inde- 
pendently of comparison with the bones of other animals. 
In a former paper attention was drawn to the equality in size 
between the fore and hind limbs of Pterodactyles; and anyone 
who examines the figures of the species longirostris, brevirostris, 
crasstrostris, scolopaciceps; longicollum, Meyeri, micronyx, &c., 
will observe that the clawed phalanges of the hand are spread 
out like those of the foot, while the wing-finger is bent back in 
front, often against the metacarpal bones. The small bones of 
the hand are often not dissimilar to those of the foot. From 
these facts, and from a consideration of the joints, I find that 
the Pterodactyle was quadruped, and, when not flying, carried 
its wings folded up in front of the fore limbs. For if it were 
true, as the restorations and figures of Pterodactyles fiying 
would lead us to believe, that the large wing-metacarpal was 
only used to support the wing, and the small metacarpals only 
used to support the claws by which the creature is imagined to 
have suspended itself like a bat, it would be impossible to believe 
that the force of flying so exactly corresponded to the force of 
suspension as to cause the large and the small metacarpals in- 
variably to attain the same length. A correspondence of this 
kind in structure, as it seems to me, can only indicate a corre- 
spondence in function ; and as the animal did not fly by means 
of its claws, the only other inference is that it walked by means 
of its metacarpal bones. There are plenty of instances of in- 
equality in thickness of metacarpal and metatarsal. bones where 
the major part of the work of running or jumping is thrown 
on some special bone, but there are probably no instances of in- 
equality in length where the function is exactly the same; and 
hence it may be shown that it would be contrary to all con- 
siderations, both theoretical and empirical, to suppose the growth 
would be the same though the functions were so different as 
those supposed. But in birds, where the functions of the dif- 
ferent metacarpals are not very dissimilar, one metacarpal is ex- 
ceedingly short ; very much less, then, could they all be expected 
