ORGAKIZATIOK OF THE OENITHOSATJHIA. 99 



part of the Ornithosaurian skeleton. In 1870, in my " Eemarks on 

 Prof. Owen's Monograph on Dimorphodon,^' I pointed out that in 

 the Cretaceous genus Ornithoclieiri{,s (PI. XI. fig. 6), the carpus 

 consists of three bones : — a proximal carpal, as in birds, which cor- 

 responds closely in form with the bone in the ostrich (PL XI. fig. 7); 

 a lateral carpal, as in birds, which I interpreted as the pisiform bone; 

 while the third bone or distal carpal of OrnitTiocheirus is, in birds, of 

 the same form, but becomes anchylosed to the metacarpus. Until 

 placed in separate genera by me*, the Cambridge- Greensand fossils 

 had been included by Prof. Owen in the genus Pterodactylus. Prof. 

 Owen now, however, in recent publications of the Palseontogra- 

 phical Society, adopts the generic groups which I suggested, but 

 discards my names, alleging that there is no evidence of avian 

 type of carpus to justify the name of OrnithocJieiriis. 



If the foregoing account of the carpus does not justify the name, 

 I might quote Dr. Rosenberg's observations f, that in early life 

 there are two elements in the distal carpal row of birds, and that 

 these carpal bones subsequently unite with each other. They 

 correspond with the four metacarpal bones of birds, and become 

 subsequently united to the metacarpus. Thus in the composite 

 structure of the carpus and in the number of metacarpal elements 

 there is an absolute agreement with the conditions in embryonic 

 or young birds, while I am aware of no such resemblances to 

 reptiles. If the fourth metacarpal of the bird becomes absorbed, 

 then Ornithocheirus apparently agrees with birds in having three 

 metacarpal bones. But it differs from birds in the distal carpal 

 (which is separated from the metacarpus) being made up of three 

 carpal elements, one corresponding to each of the three metacar- 

 pal bones — although in the mature animal the metacarpals are 

 not always attached to their corresponding carpal ossifications. 

 The distal carpal bone of Crnithoclieirus sometimes shows on its 

 proximal surface a T-shaped groove ; and occasionally the sutural 

 surfaces indicated by this groove remain unattached to each other. 

 Hence the bones are placed one above the fork of the T, and one 

 on each side of its stem ; so that they are not arranged in one line, as 

 is usual, but in two lines. These three bones are probably the 

 trapezoid, the magnum,and the unciform (PI. XI. fig.9). Themiddle 

 bone of the T, I regard as the magnum squeezed out from between 

 the other two, as is the case with the same bone in the horse and 



* ' Index to Secondary Reptilia,' &c., 1869, and ' Ornithosauria,' 1870. 

 t Quoted in Foster and Balfour's ' Embryology,' p. 175. 



