EXTINCT REPTILES . 
209 
or its fourth toe; but those who have patience to examine 
the minutiae of this structure, will find in it an exemplifica¬ 
tion of the general principle, that things apparently minute 
and trifling in themselves, may acquire importance, when 
viewed in connection with others, which taken singly 
appear equally insignificant. Minutiae of this kind, viewed 
in their cogent relations to the parts and proportions of 
other animals, may illustrate points of high importance in 
physiology, and thereby become connected with the still 
higher considerations of natural theology. If we examine 
the forefoot of the existing Lizards, we find the number 
of joints regularly increased by the addition of one, as 
we proceed from the first finger, or thumb, which has 
two joints, to the third, in which there are four ; this 
is precisely the numerical arrangement which takes place 
in the three first fingers of the hand of the Pterodactyle. 
Thus far the three first fingers of the fossil reptile agree in 
structure with those of the forefoot of living Lizards ; but 
as the hand of the Pterodactyle was to be converted into 
an organ of flight, the joints of the fourth or fifth finger 
were lengthened to become expansors of a membranous 
wing. As the bones in the wing of the Pterodactyle thus 
agree in number and proportion with those in the forefoot 
of the lizard, so do they differ entirely from the arrange¬ 
ment of the bones which form the expansors of the wing 
of the bat. The total number of toes in the Pterodactyles 
is usually four ; the exterior, or little toe, being deficient : 
if we compare the number and proportion of the joints in 
these four toes with those of Lizards, we find the agree¬ 
ment as to number, to be not less perfect than it is in the 
fingers ; we have, in each case, two joints in the first or 
great toe, three in the second, four in the third, and five in 
the fourth. As to proportion also, the penultimate joint is 
always the longest, and the antepenultimate, or last but two, 
the shortest; these relative proportions are also precisely 
the same, as in the feet of lizards. The apparent use of this 
disposition of the shortest joints in the middle of the toes of 
the Lizards, is to give greater power of flexion for bending 
round, and laying fast hold on twigs and branches of trees 
14 
