Orni'Jiosaurian Genus Oiiiitlioclieiriis. 531 



minatiou ^. An examiuatiou of this specimen shows that 

 the bone at the junction of the parietal and occipital regions 

 is raised into a ridge, which is continued laterally, forming 

 tlie margin of the hinder border of the supratemporal fossae. 

 This edge is much worn, but it is clear that it was produced 

 upwardly and outwardly, and formed no part of a backwardly 

 directed crest. Seeley f remarks that the occiput is flat, 

 but, if the borders were perfect, there would be a slight con- 

 cavity. Above the foramen magnum are the remains of a 

 vertical ridge. Its present vertical extent is 6 mm., its 

 probable length in life 10 mm. Its greatest breadth is only 

 4 mm. It is very insignificant, and no more than the ridge 

 along the line of the median union of tlie occipitals, as in 

 many of the lleptilia. The angles at which the sides con- 

 verge prove its posterior termination to have been near, with 

 no production backwards as a crest. Seeley + says " it may 

 have given attachment to a bone like that post-superoccipital 

 crest desciibed by Quenstidt in the Pteroductylus suevicus." 

 The surface is very small, and larger by being worn to its 

 base, therefore no bone of any extent or strength could liave 

 been attached here. Moreover, as will shortly be shown, 

 the crest of Ornitliostoma {Pteranodon) arises superior to, 

 overhangs, and has no connection whatever w^ith, the occipital 

 area. In Seeley^s figure this ridge, whicli is depicted with too 

 great a vertical exten>ion, does not approach so close to tlie 

 foramen magnum. The brain-ease and occiput are expanded, 

 totally unlike the compressed condition in Oniilhostoma 

 {Pierajiodon), and, by its form, it suggests relationship with 

 the toothed and pointed jaws. The sagittal crest of the genus 

 Ornithocheirus is a myth. The supratemporal fossae were appa- 

 rently narrow and deep, with the parietal region of the skidl 

 constricted, as in Onutliodesmus latkleus. No post-temporal 

 fossae are observable. There is nothing in the Cambridge 

 material to prove the absence or presence of an antorbital 

 Aacuity. The facts do not favour an Ornithostoma (Ptera- 

 nodon]-Y\^Q skull, but one with a general form corresponding 

 to the shrewd restoration of Pterodactijlus compressirostris by 

 Owen § and classified by authors under this very genus Orniiho- 

 cheirus. The specimen J. c. 8, 2 was S( eley's type for the back 

 of the skull of Ornitliocheiuts, and the only hinder region of 

 the skull, other than J. c. 8, 1, known to him. It is very 

 remarkable that all the while the Cambridge material actually 



* H. G. Seeley, Ann. .t Mag. Nat. Hist. (6) vol. vii. p. 443 (1801). 

 t H. ' Ornitlio.sauiia," 1870, p. 84. 

 t Id. ibid. p. 84. 



§ R. Owen, Cret. Kep. (Mon. Pal. Soc. ISol) pi. xxvii. fi<r. 1. 



3G* 



