CRETACEOUS FORMATIONS. 5 



slightly convex below, and as slightly concave above, vertically ; the upper margin 

 showing no indication of any bend or inclination to the upper border of the jaw, the 

 height or vertical diameter of which remains conjectural ; that it was, at least, one 

 third more than the portion preserved, may be estimated from the extent of the socket 

 of the tooth being equal with the preserved part of the wall (fig. 6, b). A coat of 

 roughish ' csementum,' one third of a line thick, is preserved upon the upper half of 

 the tooth-root ; below this is seen the smooth dentine ; and where it is broken, the pulp- 

 cavity is exposed, filled by the Green-sand matrix. The length of the implanted part 

 of this tooth is 1 inch 4 lines, the long diameter of the transverse fracture at the base 

 of the crown is \ an inch, the short diameter is 4| lines. Estimating the length of the 

 exserted enamelled crown to equal that of the inserted cemented base of the tooth of 

 a Pterodactyle — and I have known it more in the long anterior laniariform teeth — we 

 may assign a length of 2 inches 8 lines to the teeth implanted in the part of the upper 

 jaw here described. The interspace between the two sockets is 3| lines, or half that 

 of the long diameter of the socket ; the plane of the opening of the socket, and the 

 interspace, present the same obliquity as they do in Pterodactylus Sedgwickii (fig. 1) ; 

 and as the proportion of the interspace to the socket is also the same, the present 

 fragment has most probably belonged to a larger individual of the same species. 

 Since the outer border of the sockets does not swell out beyond the outer wall of the 

 jaw, the fragment has been part of jaw behind the anterior swelling caused by the 

 proportionally large prehensile teeth ; and as, from the analogy of known Ptero- 

 dactyles, the teeth succeeding those anterior ones are not of larger size, but are 

 usually smaller, at any posterior part of the jaw, we may, therefore, with due 

 moderation, frame an idea of the Pterodactyle to which the maxillary fragment (fig. 6) 

 belonged, as surpassing in size that to which the portion of jaw (fig. 1) belonged, in 

 the proportion in which the socket in fig. 6, a, exceeds the last socket in fig. 1, b. 

 Such an idea impels to a close scrutiny of every character or indication of the true 

 generic relation of the present fragment in the Reptilian class ; but the evidence of the 

 large and obviously pneumatic vacuities, now filled by the matrix, and the demon- 

 strable thin layer of compact bone forming their outer wall, permit no reasonable 

 doubt as to the pterosaurian nature of this most remarkable and suggestive fossil. 

 All other parts of the Flying Reptile being in proportion, it must have appeared, with 

 outstretched pinions, like the soaring Roc of Arabian romance, but with the demo- 

 niacal features of the leathern wings with crooked claws, and of the gaping mouth 

 with threatening teeth, superinduced. - 



The last portion of jaw of Pterodactyle from the Cambridge Green-sand which 

 will here be described, is that figured in Tab. I, fig. 7, a, b, c, d. It is part of the 

 lower jaw, and indicates a smaller individual of Pterodactylus Sedgwickii than the 

 specimens, figs. 1 and 2. In a longitudinal extent of 2| inches, six successive sockets 

 are shown, but with only the two middle pairs perfect. Their orifices have the same 



