Orniihosaw'ian Genus Ornitlioclieirns. 555 



the premaxillfe. Group A certainly approaches Ornitho- 

 desmiis latidens, hnt differs considerably iu the great inflation 

 of the ventral surface, the depth of the preaxial border, the 

 lack of any drawing in of its distal termination into a 

 tubercle, and no prolongation of the dorsal surface of the 

 bone over the preaxial border as a wing. The longitudinal 

 ridge on the dorsal surface is not as highly developed. Tlie 

 ventral suif'ace of Ornit'wdesmus latidens is deeply concave, 

 especially towards the posiaxial border, before the rise of the 

 bone for the articular facet, where, in the Cambridge specimen, 

 the convexity is the greatest, and the articular facet on the 

 postaxial side is more oblic^ue. 



The Car pals. 



It is impossible to assign any of these bones to any given 

 genus, but two which have been figured by Seeley in ' Orni- 

 thosauria' are sufficiently close to Orniihodesnius latidens to 

 favour an assumption that they belong to a genus with the 

 humerus of the type of Group A. These bones are J. b. 1, 

 no. 7, |)1. V. fig. 3, a proximal belonging to the right carpus, 

 and J. b. 3, 24', pi. v. fig. 7, to the right distal carpal. 



The Wing Metacarpal. 



As with the other bones, only fragments of the wing 

 metacarpal occur, and therefore comparisons with other 

 genera from the length cannot be made. The best-preserved 

 proximal end is J. 6. 5, 3, figured by Seeley (pi. vi. figs. 2 

 & 3j. It api)ears to belong to an entirely difierent family 

 from Ornithodesiaus. 



Several specimens possess the facet, below the main 

 proximal articulation, for the bending of the wing ; but 

 they are not as developed or directed outwards in as great 

 a degree as in Ornithodesnius latidens. 



The Sternum. 



The anterior projecting process is the only part of the 

 sternum preserved. It was dii'ccted well forward, down- 

 ward, and oblique to the sternal plate, and not vertical as in 

 Ornithodesnius latidens. They are all close to Ornithostuma 

 {Pteranodon) and Nyctosaurus, but they cannot be appor- 

 tioned either to the dentigerous or edentulous forms of the 

 Cambridge Grcensand for certainty. 



