30 Mr. H. G. Seeley on the Structure of 



upon the subject in the special monograph ' Ueber Pterodac- 

 tylus suevicus '* : — 



'' The liead, 5 inches 10 lines (Paris) long, has suffered 

 somewhat through pressure, and might therefore be considered 

 inferior in some respects to that of [P.] crassirostris. Also 

 all the teeth have fallen out ; I have vainly endeavoured to 

 trace their alveoli. It is noteworthy that the points of several 

 of the teeth appear to be cut off. The fang and crown can be 

 recognized ; and the enamel is not in ridges, but only in wave- 

 like folds. 



" The lower jaw, 4 inches 5 lines long, displays the lower 

 sm-face in a way hitherto unequalled. The symphysis alone 

 measures 1 inch 8 lines, and is 6 lines wide behind. The 

 symphysis proves how accurately Miinster has expounded the 

 lower jaw. Its surprising resemblance to the upjjer beak of a 

 water-fowl was calculated, however, to lead any one to Wag- 

 ner's different interpretation f- There is no trace whatever of 

 a suture in the sympliysis ; and no nerve-pores, found so nu- 

 merously in birds, can be seen at the foremost extremity. 

 The indents fm-ther back appear to be chiefiy due to pressure. 

 A transverse section shows clearly that the whole symphysial 

 region is parallel to the upper surface. The part which is 

 arched over is made up of several elements, although it is diffi- 

 cult to obtain a true conception of tlicir outlines. In continua- 

 tion of the dentary bone (1) lies the superangular bone (4), 

 with the angular bone (2) continuous with them on the inside. 

 The thickened articular bone, at the proximal end, cannot be 

 mistaken ; its small hindmost continuation was somewhat 

 larger in the living animal. Although one fancies one sees 

 the hollow of the articulation, it is to be presumed that it did 

 not lie on that side, but underneath, on the side which is 

 averted from the eye. 



" The upper jaw, again, has in front very much the form of 

 a beak ; but, unfortimatcly, the anterior end has suffered from 

 a forcible twisting. Tlie bone is therefore seen from above in 

 front ; and the fiuther back it goes the more it is seen from the 

 side. The nasal bones are well defined, and as the front end 

 of the bone near them is perforated like the lower jaw, it 

 seems as if the entrance to the nostril had been here, as is the 

 rule with birds. In that case the aperture, which occurs fully 

 2 inches behind the extremity of the jaw, would have nothing 

 to do with the anterior nares. In the forward part of this hole 

 lie two bones, similar to each other (16), which become thinner 

 further back : they are the vomers. On the hind part of the 



* 4to (Tiibingeu), 18oo, pp. 38-40. 

 t Akademie z\\ Miiucben, vi, p. 156. 



