176 FLYING SAURIANS. 



detail, as they afford coincidences with the bones in the cor^ 

 responding parts of Lizards, from which important conclu> 

 sions may be derived. 



As an insulated fact, it may seem to be of little moment, 

 whether a living Lizard or a fossil Pterodactyle, might have 

 four or five joints in its fourth finger, or its fourth toe; but 

 those who have patience to examine the manutise of this 

 structure, will find in it an exemplification of the general 

 principle, that things apparently minute and trifling in them- 

 selves, may acquire importance, when viewed in connexion 

 with others, which, taken singly, appear equally insignifi- 

 cant. Minutiae of this kind, viewed in their conjoint rela- 

 tions to the parts and proportions of other animals, may il- 

 lustrate points of high importance in physiology, and there- 

 by become connected with the still higher considerations of 

 natural theology. If we examine the fore-foot of the exist- 

 ing Lizards, (PI. 22, b.) we find the number of joints regu- 

 larly 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 ar-^ 

 rangement which takes place in the first three fingers of the 

 hand of the Pterodactyle; (PI. 22, c. d. e. n. o. Figs. 30 — 

 38. Thus far the first three fingers of the fossil reptile 

 agree in structure with those of the fore-foot of living Li- 

 zards; but as the hand of the Pterodactyle was to be con- 

 verted into an organ of flight, the joints of the fourth, or 

 fifth finger were lengthened, to become expansors of a mem- 

 branous wing.* 



* Tlius in tlie p. Longirostris (PI. 21, 39—42.) and P. Erevirostris, (PI. 

 22, Fig. O, 39—42,) the fourth finger is stated by Cuvier to have four 

 elongated joints, and the fifth or ungu;ii joint to be otr.iltcd, as its presence is 

 unnceessury. In the P. Crassirostris, according toGoidfuss (Pi. 22, Figs, a, 

 N,) this claw is present upon the fourth finger, (43) which thus has five 

 bones, and llie filth finger is elongated to carry the wing. Throughout all 

 these arrangements in the fore-foot, the normal numbers of the type of Li- 

 zards are mainlaitied. 



If, as appears from the specimen engraved by Goldfuss, of P. Crassi- . 



