FOSSIL REPTILIA OF THE 



Pterodactylus Sedgwickii, Oiven. Jaws and teeth, Tabs. I and III. 



The specimen (Tab. I, fig. \, a,h, c, d) is the fore part of the upper jaw, contain- 

 ing the first seven sockets of the teeth, in a few of the anterior of which the base of 

 the tooth is retained. The first two sockets open upon the obtuse extremity of the 

 jaw (fig. 1, c), and have a direction showing that their teeth projected obfiquely 

 forward, so as to prolong the prehensile reach of the jaw ; the second and third 

 sockets are the largest, and cause a slight transverse swelling (fig. \,h) ; the fourth is 

 suddenly smaller, and the three following retain nearly the same size, or show a slight 

 increase as they pass backward. The apertures of the sockets are elliptic, wath the 

 long axis extending obliquely from before outward and backward, not parallel with 

 the axis of the jaw ; the plane of the outlet inclines slightly outward (fig. 1, c). The 

 interval between two sockets is about half the long diameter of each. On one side 

 of the figured specimen the fifth socket is obliterated. The anterior termination of 

 the jaw is obtuse ; the sides are smooth, flat, converging at an acute angle to what 

 almost forms a ridge above (fig. \,c,d) ; the jaw gradually increases in vertical diameter 

 as it proceeds backward, the upper contour being straight as far as it can be traced 

 in the fossil. The palatal surface is entire, narrowest between the second sockets, 

 suddenly broader and flat between the third pair, retaining about the same breadth, 

 but with a slight convexity and feeble indication of a median ridge in the rest of its 

 extent, the ridge not being so strongly marked as it appears in fig. 1, h. 



The Pterosaurian nature of this fossil is shown by the extreme thinness of the 

 compact bony wall of the jaw ; its relation to the genus Pterodactylus, as contra- 

 distinguished from the Rhamphorhynchus, V. Meyer, is proved by the terminal posi- 

 tion of the sockets ; and sufficient of the outer side wall of the jaw is preserved to 

 show that the nostril did not advance so far forward as in Dimorphodon — the generic 

 form of Pterodactyle from the Lower Lias. 



By its size and true or proper Pterodactyle affinities the present specimen most 

 resembles Pterodactylus Cuvieri of the Chalk, (Monog. cit.. Tab. XXVIII) ; but it 

 offers the following well-marked differences : a greater proportional size of the 

 anterior sockets, with a corresponding expansion of the fore part of the jaw ; a 

 greater number and closer arrangement of the sockets ; a greater depth of the jaw, 

 in proportion to the breadth of the palate. The extent of the jaw, e. g., containing the 

 first seven sockets, in Pterodactylus Sedgwickii, is 2 inches 9 lines ; but in Pterodactylus 

 Cuvieri it is 3 inches 6 lines : the depth of the jaw, above the third socket, in Pter. 

 Sedgwickii, is 14 lines ; in Pter. Cuvieri it is 8 lines ; whilst the breadth of the palate 

 between the third pair of sockets is only 1 line less in Pter. Cuvieri than in Pter. 

 Sedgwickii. It needs only to compare the fore part of the jaw of the Great Chalk 



