1845.] OWEN ON SUPPOSED BIRDS* BONES IN THE WEALDEN. 97 



Fig. 2. 



matrix that adhered to its extremity Fig. 1, 



some characters not visible when the 

 fossil was first submitted to me, and 

 having been led by those new charac- 

 ters to institute a more extended and ri- 

 gorous comparison of the fossil than it 

 was in my power to do ten years ago, I 

 believe myself in a condition to demon- 

 strate my former error in ascribing it to 

 the class of Birds, and I therefore lose 

 no time in rectifying it. The character 

 mainly relied on as proving the fossil 

 in question to be the lower end of a tar- 

 so-metatarsal bone of a wading bird, was 

 the rough oval spot marked o in fig. 1 b, 

 pi. 13, of the above-cited volume, 

 and this, if interpreted as the articular 

 surface for the hind-toe, would indi- 

 cate a form of metatarsal bone like 

 that of the restored figure given by Dr. 

 Mantell, by the dotted outline in the 



above-cited plate. But the characters Anterior or palmar aspect of the distal 

 I 1 J i !• 1 i ii 1 end of the humerus of a Pterodactvle. 



Smce brought to light prove the bone Wealden. (Natural size.) 



(fig. 1) to have terminated much nearer 

 the oval spot (o), since they consist 

 of two portions of the distal smooth ar- 

 ticular surface, one (a, fig. 1 & 3) situ- 

 ated near the margin of one side of the 

 joint, at right angles to the axis of the 

 bone ; the other surface (b) being a 

 smooth protuberance near the middle 

 of the concave side, but at the end 

 where the small mass of light-coloured 

 matrix appears in Dr. Mantell's figure 

 1 b. Now, as these surfaces have 

 formed part of the articular extremity 

 of the fragment, and establish its true 

 position, traces of the vertical or lon- 

 gitudinal fissures separating the con- 

 dyles ought to be present, if the fossil 

 were actually part of a tarso-metatarsal 

 bone, and more especially on the con- 

 vex side, fig. 2 ; for in none of the 

 tarso-metatarsal bones of the numerous 

 birds which have been compared with 

 the fossil, are the grooves or foramina, 



indicativp of f hp divkinn* nf fhp pnd of Posterior or anconal aspect of the distal 

 HlUlCdllve OI me ai visions OI ine enu OI end of the humerus of a Pteroductjic. 



the bone for the trochlear joints of tlie Woaidcn. (Natural size.) 



toes, entirely absent, as they are in the smooth, slightly undulating 



convex surface of the expanded end of tlic fossil. 



VOL. II. PART I. u 



