92 MB. H. a. SEELET OS THE 



No omitliosaurian fossil has displayed the undisturbed palatal 

 aspect of the skuU ; but in CycnorJiamphus suevicus and Pachy- 

 rhampTius crassirostris the palatal bones may be detected as 

 slender elements comparable to those of birds. The palate of 

 Pachyrhamphus may have approximated towards the palate of 

 such a struthious bird as the Emu ; but CycnorhampJius had a 

 palate more like that of a natatorial or gallinaceous bird, as I have 

 already tried to show in a published restoration *. In neither of 

 these genera, nor in any known Ornithosaur," have the palatal 

 bones any reptilian features. 



Formerly considerable weight was given to the occurrence of 

 teeth in Ornithosaurians as a point of resemblance to reptiles ; 

 but this feature is now balanced by the occurrence of similar 

 teeth, according to Professor Marsh, in the jaws of the cretaceous 

 birds Hesperornis regalis and Ichthyornis dispar f, as well as by 

 the presence of teeth anchylosed to the jaw in Odontopteryx %• 

 Since Hesperornis possesses so many of the characters of existing 

 birds, there seems to be no reason why the occurrence of teeth 

 in Pterodactyles should be regarded as a character more reptilian 

 than avian. Some years ago I pointed out that since the teeth 

 in the maxillary bone in the Delphinidse are all simple and 

 conical with one fang, the occurrence of teeth similarly simple in 

 Ornithosaurians is no more a resemblance to reptiles than it is to 

 mammals, and is therefore valueless as a mark of affinity. The 

 tooth-structure is not very like that of any living animal. 



When printing my book on the Ornithosaurians, I stated that 

 the teeth resembled those of some mammals in the dentinal cells. 

 The point always appeared to require further examination ; and 

 beautiful new sections made for me by Mr. Cuttell, of New 

 Compton Street, demonstrate no such structure. From studies 

 of sections of teeth, it seems to me that we can by no means cer- 

 tainly determine, on microscopical evidence, whether a tooth is 

 reptilian or mammalian, especially when the type to which it be- 

 longed is extinct. 



In longitudinal sections of the tooth of OrnithocJieirus from fang 

 to crown (PI. XI. fig. 11) the calcigerous tubes radiate as in the 

 teeth of Ichthyosaurs and Plesiosaurs ; they are wavy tubes which 

 occasionally bifurcate, but are remarkable for the many branches 



* Ann. Nat. Hist. 1871, vol. vii. pi. 2. 



t Am. Joiir. Sci. vol. x. 1875, pi. 10. 



\ Quart. Joiirn. Geol. Soc. vol. xxix. pi. xvi. 



