256 BRITISH FOSSIL REPTILES. 



is a character of the proximal end of tlie first phalanx of the wing-finger, but no 

 part of the articular surface has been preserved. 



A similar portion of the corresponding bone of the opposite wing is figured in 

 PI. 5, fig. 2, and the more frequent occurrence of long bones with the subtriedral 

 shaft, showing a contraction and deepening of the narrowest of the three sides towards 

 one of the expanded ends of the bone, and the presence of the pneumatic foramen in 

 the groove so formed, would indicate them to be one of those bones that are present 

 in greatest number in the framework of the wing of the Pterodactyle, viz., phalanges 

 of the singularly long and strong wing-finger. 



The fragment of the shaft of a bone, with a wide cavit}^, PI. 5, fig. 3, shows 

 a different shape from most of the long bones above described ; its transverse section 

 is given at fig. 3' ; and from its shape, and the presence of a longitudinal ridge at 

 one side of the flatter and probably posterior part of the shaft, I am inclined to regard 

 it as having been part of a femur ; it bears the same proportion to the diameter of the 

 humerus, PI. 2, fig. 1, as the femur of the Pterodadylm crassirostris does to the 

 humerus, in the beautiful plates of the Memoir by Goldfuss, above quoted. 



The fragments of long bones, with the best preserved articular extremity, are 

 those represented of the natural size in PI. .5, figs. 4 and 5, the former of which was 

 originally figured in the ' Geological Transactions,' 2d Series, vol. vi, pi. 39, fig. 2, 

 the latter in the ' Quarterly Journal of the Geological Society,' vol. iv, pi. ii, fig. 4. 



Both these bones offer the closest resemblance to the trochlear modification of the 

 lower end of the tibia in the bird ; and, if we might presume on that analogy, it would 

 be to the same bone in the gigantic Pterodactyle, that we should, also, refer them, 

 with the present indubitable evidence of the existence of volant reptiles of such 

 dimensions in the formation and localities whence the specimens in question have been 

 derived. But it is not likely that a reptile with distinct tarsal bones would have the 

 same modification of the distal end of the tibia as in the bii'd, which does not possess 

 them. 



The specimen which is the subject of fig. 5, in PL 5, was obtained by J. Toulmin 

 Smith, Esq. from a chalk-pit near Maidstone, and has not suffered the degree of com- 

 pression which distorts the specimen, fig. 4, PL 5, which was obtained by the Earl of 

 Enniskillen from the same pit. The obliquity of the two parallel, convex, narrow 

 condyles, which I suspected might be the effect of crushing in fig. 4, is shown to be 

 natural in fig. 5 ; the back part of each condyle is broken away, but their antero- 

 posterior extent is fortunately shown in fig. 4. The shaft is naturally compressed from 

 before backwards, as is shown by the section, fig. b", and by the side view fig. 5'. 

 There arc two depressions and two rough elevations on the surface of the bone, fig. 5, 

 and between the latter a groove extends longitudinally, as if for the passage of a 

 strong tendon ; the vacuity in the thin parietes of the bone above the condyle is, I am 

 assured by Mr. Smith, a natural one, which he himselfexposed upon carefully removing 



