488 BRITISH FOSSIL REPTILES. 



most resemblance to the Pterosaurian tympanic.^ For, besides the Lacertian freedom of 

 the bone from zygomatic abutment, the tympanic in the Chameleon has not the 

 longitudinal strengthening ridges, nor the process turned toward the pterygoid. 



The dentigcrous mandible, like the maxilla, speaks for the Reptilian afhnity of 

 Pterosauria ; the distinct sockets for the teeth ally them to the higher forms of Sauria. 

 In reference to the generic modification of dentition in Dimorphodon, it has been remarked 

 that this early form of flying dragon seemed to have derived one feature or modification 

 from the Fish, and the other from the Crocodile or Plesiosaur.^ 



The length of the neck, which is not always equal to that of the head, is due, in 

 Pterosauria, rather to the length than the number of the vertebra?. Counting the axis 

 with the small coalesced atlas ^ as one, I give seven cervical vertebrae to the Dimorphodon 

 macronyx (PI. 17, fig. 1, c). Of these a series of four are preserved in the specimen (PI. 

 16, c), showing, as described, the characteristics of the Pterosaurian cervical vertebrae 

 which had been determined and illustrated in a former Monograph.* 



CuviER,^ in his searching analysis of the evidence at his command of the osseous struc- 

 ture of the Pterodactylus lonyirosfris, concluded that the cervical vertebrae were not fewer 

 than seven, as m Crocodilia and Mammalia, or not more than eight, as in Chclonia. 



GoLDFUSS was able to demonstrate the vertebral formula in his famous specimen of 

 Pterodactylus crassirostris.^ The number, ' seven,' was, however, obtained by reckoning 

 the atlas distinct from the axis, and the last cervical may have been relegated to the 

 dorsal series. 



Quenstedt' shows seven cervicals in his instructive example of Pterodacfylus siievicus, 

 reckoning the atlas and axis as one vertebra ; and this analogy I have followed in the 

 restoration of DimorpJiodon. 



Rhamp/iorhynchus Gevimingi has six cervicals, counting the coalesced atlas and axis as 

 one ; but in the specimen figured by Von Meyer in his pi. ix,^ there seems to be the centrum 

 of a short ' seventh ' cervical between the longer ' sixth ' and the first (dorsal) vertebra 

 supporting a long free pointed rib. It is certain that the number of cervicals does not 

 exceed the latter reckoning or fall short of the first. Thus it is plain that the Pterosauria 

 exemplify the Crocodilian affinity in the cervical region of the vertebral column. Lacer- 



' " Dieser Knochen ist nicht wie in den Vogeln quadratisch, sondern cylindrisch stielformig 

 beschaffem. — Hierin, so wie in eininpjen andern Tlieilen, zeigt das Tliier die meisle Aehnlichkeit niit Cha- 

 maeleonT — Von Meyer, op. cit., p. 16. 



^ 'Report (Sections) of the British Association for the Advancement of Scienre,' 8vo, 18.t8, p. 98. 



3 Pterosauria, PI. 7, figs. 11—14. 



* PI. 8. PI. 12, figs. 1, 2 and 4. 



^ 'Ossemens fossiles,' torn, cit., p. 367. 



^ "Man ziihlt 7 Halswirbel, 1.5 Rippenwirbel, 2 Lenden, and 2 Kreuzbeiiiwirbcl," loc. cit., p. 79. 



7 Op. cit., figs. 1—7. 



8 Op. cit. 



