402 MR B, . W. HOOLEY ON IHM [June 1913, 



does not apparently do this for more than 3 mm. anterior to the 

 fracture. The nasals thus occupy their usual position interior to 

 the prefrontals. Such being the case, they are situated as in 

 ■Scapkognathus crassirostris and Dimorphodon maeronyx. 



The Quadratojugal. 



The union of the quadratojugal with the maxilla, as has been 

 pointed out by Dr. G. Baur, 1 is a character of the Sauropoda : he 

 instances Diplodoeus. It is seen in the Ornithopoda, for Iguanodon 

 xeveals a like arrangement, and also in the Amphibians Ohely- 



dosaurus vranyi (Frjtsch) and Dendrerpeton pyriticum (Fritsch). 



The quadratojugals of Dimorphodon maeronyx and ScapTiognatlvus 

 purdoni are triangular plates and placed vertically, and therefore 



differ from the quadratojugal of Omitliodesmus latidms. In 



Rhampliorhynclius, Ornithostoma, and Nyctosaurus they more or 



less approximate to this form. 



The Quadrate. 



Zittel 2 notes, as a character of the Pterosauria, that the inferior 

 •articular surface of the quadrate finishes in front of the middle of 

 the orbit : thus, if we except Ornithostoma, where it is slightly 

 in front, Omitliodesmus laiidens is quite peculiar. The manner 

 •of the proximal union of the pterygoids with the quadrates of the 

 European forms is as yet obscure, but there is not much doubt 

 that distally it is effected in both tScaphognathus and Omitliodesmus 

 by means of a rod-like bar from the pterygoids. The plain pulley- 

 articulation of 0. latidms is very different from the spiral groove of 

 •Ornithostoma (Pteranodon). 



The Teeth. 



The arrangement of the hinder teeth is unique. Several of the 

 •teeth of the upper jaws of Dimorphodon and Scaphognathus overlap 

 the lower jaws. The teeth iu Pterodactylus antiquus and Ft. suevicus 

 occur much in advance of the nares, whereas in Omitliodesmus the 

 nasal openings begin near the last teeth. In the former genus the 

 teeth are short and conical, thus differing from the lancet-shaped 

 teeth of Omitliodesmus. These lancet-like teeth are vertically 

 placed, set in the alveolar border with great regularity, and these 

 •conditions, combined with their complete interlocking, constitute 

 exceptional traits. The nearest approach is found in some of the 

 fragments of jaws from the Cambridge Greensand that are included 

 in the genus Omithocheirus. In the type-specimen of Sea phogna thus 

 purdoni the alveoli appear to show that the teeth were slightly 7 

 compressed laterally, and thus are nearer the dentition of Ornithy- 

 ■desmus. 



1 Geol. Mag. dec. 3, vol. vi (1889) p. 173. 



- K. A. Zittel, ' Trait 6 de Paleontologie ' vol. iii (1893) p. 773. 



