Mr. H. Seeley on the Avian Affinities of Pterodactyles. 327 
This alone is ample evidence, were there no other, that our ani- 
mals were near allies of the birds; but it will be seen that the 
correspondence is not limited to the general principle of organi- 
zation, but extends to many of its details. 
I have been able to examine fragments of several skulls from 
the Cambridge Greensand, one of which is of great size, and 
shows the interior of the front part of the skull, exhibiting the 
form, size, and characters of the front part of the brain. The 
brains of birds and reptiles are both so characteristic that there 
can be no doubt about the conclusion to be drawn from this 
evidence. In Pterodactyles the large hemispheres are extremely 
high, and terminate in front in well-rounded convexities, between 
which there is a little depression. This is most characteristically 
avian, and would be quite sufficient to show that the Pterodac- 
tyles ought not to be expected to have any resemblance to rep- 
tiles. I have also been able to examine three skulls of which 
the occipital and parietal regions are well preserved, and can 
confidently assert that the brain is not less developed than in 
birds; indeed it is only by some minor modifications of the 
basal region that any one could distinguish the skulls from those 
of ordinary birds. There is nothing in the brain to show that 
the Pterodactyles were not more highly organized than birds. 
Although Pterodaectyles were quadrupeds, they were flying 
quadrupeds ; and it has been generally assumed that they flew 
by means of membranous wings, like the mammalian bats. But 
their wings have little in common with the mammalian wing, 
not being formed by prolongations of all the fingers; and no 
reptile known, from recent or fossil specimens, has wings. There- 
fore there only remains the birds with which the Pterodactyle 
wing can be compared; and with them, as will be seen, the 
correspondence of plan is perfect. In ordinary birds it is sin- 
gularly close, but in the Archeopteryx it is closer. Each of 
these groups of animals has a well-developed humerus, and ulna 
and radius not very dissimilar, as was to be expected. In both, 
the carpals are short, small bones; in both, the metacarpals are 
long, slender bones: there are three in ordinary birds (one 
short), four in the Archeopteryx, and four in most known Ptero- 
dactyles. In ordinary birds, one of the fingers which these 
support sometimes terminates in a claw; in Archeopteryx two of 
the fingers appear to terminate in claws, while in Pterodactyles 
three of the fingers have claws. In birds two of the metacarpals, 
more or less anchylosed together (and therefore functionally one), 
with their phalanges, terminate the wing; but in Pterodactyles 
there is one large metacarpal which supports a number of long 
phalanges, varying to as many as four, while in birds the num- 
ber is usually limited to two. Thus, however dissimilar they 
