CRETACEOUS PTERODACTYLES. 439 



The fifth socket (p), the fore part of which is preserved on the right side, is four 

 lines distant from the fourth. 



The thinness of the compact outer wall of this fragment of the upper jaw, and 

 the large size of the cancelli, concur with the dental characters in demonstrating 

 the Pterosaurian nature of the fossil. So far as the outer wall is preserved it shows 

 no trace of the external nostril at a distance, viz. of three inches from the fore part 

 of the upper jaw. 



The tooth in place is sub-compressed, conical, long, and slightly curved, with 

 the convexity forward. The portion of enamel preserved on the crown accords 

 with the Pterosaurian type of tooth in its thinness, in the very delicate, irregularly 

 wavy, sometimes branching, longitudinal ridges, on its outer surface ; the dentine 

 is compact, and is coated by cement at the base of the tooth. 



Pterodactylus Woodwardi. pi. 12, figs. 3, a, h, c. 



The specimen from Professor Sedgwick's collection, represented of the natural 

 size in PI. 12, fig. 3, a, j, is a transverse fragment of the jaw of a Pterodaciyle, 

 from the Upper Green-sand of Cambridgeshire, showing a greater divergence of 

 the side walls towards the alveolar or oral surface, and, consequently, greater 

 breadth of that surface in proportion to the height or vertical extent of the part 

 than in the Pfer. sinms. Of the oral surface too small a portion is preserved to 

 indicate whether it be palatal or mandibular. By the characters of the median 

 ridge or groove pointed out at pp. 381, 381, I incline to regard it as part of the 

 upper jaw, corresponding in the proportions of height and palatal breadth with 

 that of the Pterodacfjjius Fitloni (PI. 7, fig. 3), but coming from a part of the jaw 

 further from the anterior extremity. 



The fractured ends show the characteristic thinness of the compact, bony wall 

 and the large (air- ?) cells occupying its substance. 



The side wall, which is most entire, has been abraded (PI. 12, fig. 3, h), but 

 the small portions of the preserved surface exhibit the smooth character of 

 Pterosaurian bone. The fragment includes a pair of sockets, with the bases of 

 their teeth. The latter show the usual elliptical, transverse section (fig. 3, e). 

 The implanted base of the tooth extends three fourths of the way to the upper 

 border of the jaw; it has a coat of cement half a line thick, with the outer surface 

 longitudinally ridged, corresponding with the grooves of the socket. The direc- 

 tion of the socket shows that the tooth extended obliquely forwards and outwards 

 as well as downwards. 



PI. 14, fig. 4, shows the part of the base and basal half of the crown of a tooth 

 of a Pterodactyle, from the Upper Green-sand of Cambridgeshire, a little sur- 

 passing in size that of which the base is shown implanted in the socket of the 



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