382 BRITISH FOSSIL REPTILES. 



answer to the second and third in fig. 1 , though there scarcely seems room for a pair 

 in advance of the foremost in the specimen figured ; be that as it maj', the distance 

 between the first and second socket in the specimen of Pterodactylus Fittoni is, 

 relatively to the size of the socket, greater than the interval between the second and 

 third sockets in Pterodactylus Sedgwickii, and much greater than that between the 

 second and third sockets in fig. 3. The outer wall of the largest anterior socket in Pter. 

 Fittoni is much less prominent than in Pter. Sedgwickii, and the lateral expansion of 

 the fore part of the upper jaw must have been relatively less ; the form of the bony 

 palate is different, there being a distinct though shallow longitudinal groove on each 

 side a low obtuse median ridge. The diastema between the second and third tooth is 

 shown to exceed the long diameter of the second socket, recalling the proportion of 

 the interspaces in Pterodactylus Cuvieri (PI. 3, fig. 4), but the jaw is broader in 

 proportion to its height in Pterodactylus Fiitoni. 



Figure 4, a and h, PI. 7, is a fragment of one side of the fore part of the upper 

 jaw, showing three alveoli, and agreeing in general proportions with the Pterodactylus 

 Fittoni. 



Fig. 5, PI. 7, is the fragment of a jaw, showing a single elliptical socket, 5 lines in long 

 diameter (a), and with the plane inclined a little outward, as at b. The widely open 

 cancellous structure of the bone is well shown on the inside of this fragment, as at c. 



Pterodactylus. Sp. inc. 



PI. 7, fig. 6, is a portion of an upper jaw, including a part of two sockets, in 

 one of wdiich the root of the tooth remains. Three views of this fragment are given, 

 of the natural size : a showing the alveolar border, h the broken margin exposing the 

 tooth, and c the outer wall of the jaw. This part of the wall is nearly flat, very 

 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, 6). A coat of 

 roughish ' caementum,' 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 the crown to be of greater length in the anterior 



