534 Mr. R. W. Hooley on tJie 



It appears that different families possessed the pectoral 

 girdle characteristic of Oniithoatumu [Pteranodon), e. g., 

 Ornithodesmus, but the form of the skull, the position alid 

 shape of the several elements, the absence or presence, size, 

 and position of the teeth, vary in the different genera, and 

 are therefore the characters most to be trusted in classifica- 

 tion. By such means the portions of skulls included in the 

 Cambridge material under the genus Omithocheirus natu- 

 rally divide into five well-defined groups, and it is more than 

 probable that they belong but to few species. The humeri, 

 and ulnae may be arranged into three groups. 



Further, Seeley ^ was misled by a study of the German 

 specimens in determining the ulna as the radius and the 

 radius as the ulna, and therefore the Avrong position of these 

 hones in the antebrachium and their place of articulation 

 with the proximal carpal, and in stating that the radius was 

 the larger bone. 



He was studying extremely fragmeutary remains, and in 

 the German specimens the bones are so crusiied that tlie 

 drtailed structure of their articulations is nearly indecipher- 

 able. 



We shall now proceed to denote the characters by which 

 the fragments of snouts may be classified, and give the 

 species wliich naturally group themselves under each. 

 !Many of the specimens are so close to one another — which 

 is remarkable in itself, considering their fragmentary state 

 — that the differences in detail, which aic often trivial, are 

 of little avail until future discoveries of more complete skulls 

 exhibit otherwise. This, we are confident from a close study 

 of these specimens, will not be tlie case, and it is strange 

 ttiat every specimen found should have Ijclonged to a new 

 species. The twenty-six type-specimens in tiie Sedgwick 

 Aluseum liave been described by Seeley or Owen ; therefore 

 it will not be necessary to do that again. 



Group No. 1. 



Beaks laterally compressed, moderate vertical dejjth, tip 

 more or less obtuse, dorsal keels. Palate curving sliglitiy 

 ujjwards anteriorly, causing the front teeth to be direcfed 

 forward. Longitudinal ridge on palate, teeth subcircuiar, 

 alveolar I'ims rising above palate. 



* n. G. Seeley, ' Oriiithosauiia,' 1870, p, 42. 



