Yol. 69.] SKELETON OE OBNJTHODESMUS LATIDENS. 395 



hollow, and are supported and braced by tbe maxillo-nasal bars. 

 A long muzzle would seem to have been more favourable for pro- 

 curing food. The use of the teeth at the extremity of such a beak 

 ■would be great if the diet consisted mainly of fishes and the smaller 

 reptilia, and was seized in flight. The teeth are admirably fitted for 

 that purpose, their interlocking gin-like arrangement being perfect 

 for prehension, so much so that no prolongation of an occipital crest, 

 •as in Ornitliostoma (Pteranodon), 1 to permit of a greater develop- 

 ment of the temporal muscles, was necessary. This was an adap- 

 tation for the same purpose by different means. Length of beak 

 is seen in such birds as herons, storks, etc., which favour a like 

 food, or as in the skimmer, Bhynchops, as mentioned by Dr. Eaton 

 {h(-. cit.). That the reptile dipped occasionally in the water in 

 pursuit of its prey is likely, but the ' power of swimming,' which 

 Euckland a thought that the Ornithosauria had, could not have 

 been possible, for not only were the limbs included in the patagium, 

 but the elbow-joint only allowed a hinge-like movement dorso- 

 ventrally, and the nature of the articulations of the carpus and the 

 wing-metacarpal with the first wing-phalange precluded the back- 

 Avard motion required. The highly-developed keel of the sternum 

 proves the reptile to have been of very powerful flight, and it is 

 interesting to recall the opinion of Hermann von Meyer 3 with 

 regard to the known Ornithosauria in 1859, that they could not 

 have been migrating animals, because there was no keel. The 

 evolution of the keel had been accomplished by the Wealden Period. 

 The position of the coracoids in flight seems to have been at right 

 ■angles to the keel, that is, with their articular ends on the coracoid 

 facets of the keel opposite one to the other, and the scapula? 

 articulating with the dorsal vertebrae. The arc-shaped coracoid 

 articular facets on the keel appear not to have been solely for 

 purposes of flight, for the semi-revolution would weaken rather than 

 strengthen the act, but to allow of the coraco-scapular arch being 

 •drawn forwards. The free articular portion of the scapula at right 

 •angles to the coracoid moiety of the glenoid cavity probably 

 gave rotating freedom to the humerus in an antero-posterior 

 direction, opposite to the supero-inferior movement in the act of 

 flapping the wings. The ordinary saddle-shaped glenoid cavity 

 permitted a much greater freedom of movement up and down, than 

 from side to side ; wherefore I suggest that the additional surface 

 was primarily evolved to allow of the humerus being directed 

 forward parallel with the long axis of the body, by a slight twist 

 •of the wings. Such a position was necessitated and assumed when 

 the reptile was hanging from a rock or bough. During suspension 

 the coracoids would also be drawn forwards, until their sternal 

 •ends overlapped one above the other as the peculiar coracoid 

 ■articulations permitted. Those forms that possessed the coracoid 



1 G-. F. Eaton, Mem. Connect. Acad. Arts & Sci. vol. ii (1910) p. 13. 



2 W. Bucklancl, Bridgewater Treatise No. 6, vol. i, 3rd ed. (1858) p. 218. 



3 C. E. H. von Meyer,"' Eeptil. aus dem Lithogr. Schiefer d. Jura ' 1860, p. 17. 



