CRETACEOUS FORMATIONS. 93 



siliceous spatli. I am not at present aware of any species of Pterodactyle in which 

 the teeth are so short and thick as in the Pt. giganteas, (see the magnified view, 

 fig. 6.) Those figured in PL 27, Vol. iii., 2d Series, of the 'Geological Trans- 

 actions/ on the supposition that they might belong to the Pterodactyle, appertain 

 to a species of Fish. The point of a successional tooth projects from the fore part 

 of the ninth socket on the right side of the upper jaw, from which its predecessor 

 has fallen, proving, as in the larger species, that the crowns of the successional teeth 

 do not emerge, as Cuvier surmised to be the case in Pt. longirostris* from a distinct 

 orifice on the inner side of the socket of the old* tooth, as in the Mammalia. 



The substance of the osseous walls of the above-described portions of jaws is as 

 thin and delicate as in the foregoing species : it does not present the same fine 

 longitudinally striated surface as in the Pt. Cuvieri ; but it is similarly perforated by 

 numerous minute vascular foramina, which are largest and most abundant near the 

 alveolar border at the fore part of the jaw. 



The unique specimen above described was discovered in the Burham Chalk-pit, 

 Kent, and is in the Collection of James Scott Bowerbank, Esq., F.R.S. 



Scapular Arch and Bones of the Extremities of the Pterodactylus 

 giganteus, Poioerbanli. Tab. XXXT, figs. 7, 8, 9, 10 — 13. 



Perhaps no part of the skeleton of the Pterodactyle more closely resembles in form 

 that of the bird, than the scapular arch : and in no specimen has this arch been better 

 preserved than in the Pterodactylus inacronyx.\ The scapula is shown in those specimens 

 to be long, sabre-shaped, and to form a moiety of the articular concavity for the head 

 of the humerus, and the coracoid to be stronger, straighter, and shorter than the 

 scapula, and with a subbifid protuberance near the articular surface for the humerus : 

 the opposite end of the coracoid terminates by a rather oblique truncation, but 

 without expanding : both the elements of the arch are anchylosed together, where they 

 meet at rather an acute angle to form the shoulder-joint. In the Pt. crassirostris% the 

 two bones appear not to have been anchylosed, the more slender and slightly curved 

 bone, l", in Prof. Goldfuss's plate, is called the coracoid, the stronger and straighter 

 one, 16, the scapula: but this determination seems to have been based upon the crushed 

 specimen, in which there has been sufficient displacement of parts to render it very 

 probable that the scapula and coracoid have suffered some change of position : the 

 fore part of 17, which I believe to be the scapula, shows a tuberosity near the articular 

 end, which forms an angle between that and the shaft of the bone: the coracoid, u;, 



* Ossemens Fossiles, torn, v, pt. ii, pp. 364, 367. 



f See Dr. Buckland's Memoir, 'Geological Transactions,' 2d Series, vol. iii, pi. xxvii, X, 9; and 

 Von Meyer, in the 'Nova Acta Acad. Nat. Curios.,' torn, xv, pt. ii, Tab. lx, fig. 8. 

 % Goldfuss, nt supra, T. VII, 16, 17. 



