Shoulder -girdle in Cretaceous Ornithosauria. 443 



(* Ornithosauria,' pi. xi. fiprs. 10-12, and Journ. Linn. Sic. 

 vol. xiii. pi. xi.) was only laid bare after I had removed a 

 great thickness of open cellular investing bony tissue from 

 above it. The skull figured pi. xi. figs. I, 2 of the { Ornitho- 

 sauria ' shows traces of an eroded crest above the foramen 

 magnum, and superiorly the external tissue of the parietal 

 region is worn away ; but there is nothing to show how much 

 has been worn away. When, however, the form of the receding 

 neural arches of the atlas and axis is compared with the back 

 of the skull, the vertebrae slope backward as though an occipi- 

 tal crest extended backward from the skull ; but it may not 

 have been so much developed as the nuchal bone in the 

 Cormorant. 



In my theoretical restoration of the skull of Ornitho- 

 cheirus, given in the Ann. & Mag. Nat. Hist., January 1871, 

 pi. iii. fig. 3, there is no antorbital vacuity in the skull, and this 

 condition was found to characterize, the American toothless 

 Ornithosaurs when Prof. Marsh figured the complete skull in 

 1884. 



There is therefore, as it seems to me, a close correspondence 

 between the skulls of the American edentulous Cretaceous 

 Ornithosaurs from Kansas, and the dentigerous genera from 

 the Upper Greensand and other Cretaceous rocks of Europe in 

 all points which can be compared ; and this I take as evidence 

 that they are closely allied and belong to the same ordinal 

 group. Mr. E. T. Newton (Proc. Geol. Assoc, vol. x. no. 8, 

 p. 421) places Pteranodon and Nyctodactylusm Prof. Marsh's 

 Pteranodontia, while Orniihocheirus and Ornithostoma are 

 placed in a division of the Pterosauria. But if Pteranodon is 

 Ornithostoma, and if the skull of Ornithocheirus is in essential 

 points on the same plan as in the American genus, I fail to 

 see how Mr. Newton's grouping can be sustained. 



There is another point of identity between the American and 

 English types in the structure of the carpus. It was no easy 

 matter to determine the mutual relations of these bones in Cam- 

 bridge specimens, for the structure was unlike anything pre- 

 viously known. They were described and figured in the ' Orni- 

 thosauria,' their relations to each other were first figured in the 

 Ann. & Mag. Nat. Hist., August 1870, in " Remarks on 

 Dimorphodon" and some further details were supplied in the 

 Linnean Society's Journal, December 1876, pi. xi. The 

 carpus consists of a proximal carpal, a distal carpal, and a 

 lateral carpal, formed as in birds. It was this evidence of 

 the structure of the hand which led me in 1869 to form the 

 genus Ornithocheirus for animals which had previously been 

 referred to the genus Ptcrodactylus. Professor Marsh finds 



