ORGANIZATION 01" THE ORNITHOSATIEIA. 101 



proximally or distally. Whatever value may be attached to the 

 resemblances of this carpus to the carpal bones of birds, it appears 

 to render a modification necessary of Prof. Huxley's statement 

 that the manus is a part of the skeleton in which birds and Pte- 

 rodactyles diverge most widely. 



Turning next to the metacarpus, I find that just as Dr.Eosen- 

 berg describes four metacarpal cartilages, as I also have observed 

 in the chicken, so Pterodactyles from the Lithographic slate have 

 four metacarpal bones — one of them more developed than in 

 birds, and three thread-like, or at least much more slender than 

 the other. The Ornithoclieirus from the Cambridge Upper 

 Greensand shows on the distal surface of the distal carpal three 

 distinct articulations for metacarpal bones, two of which have 

 articular surfaces of not dissimilar size ; and these seem to me to 

 correspond to the two elongated metacarpal bones of birds. The 

 fact of the metacarpal bones not being anchylosed together has 

 never been thought to militate against the systematic position of 

 ArchcBopteryx as a bird. Like the blended characters of the meta- 

 tarsus in birds, it is so certainly functional that I am not disposed 

 to regard the separate condition of the metacarpal bones either as 

 a very important character, or as an evidence of reptilian affinity 

 in Ornithosaurs. The Pterodactylian metacarpus, then, as Pro- 

 fessor Owen has demonstrated, does not diverge greatly from the 

 metacarpus of Archceopteryx. 



The resemblance of the wing-digit to that of a bird is very 

 remarkable, since the difference chiefly consists in the introduc- 

 tion of extra phalanges into the Ornithosaurian wing-finger. 



There is felt by some writers to be a difficulty in accepting any 

 modification of the old interpretation of the Ornithosaurian hand, 

 on account of the number of phalanges in each of the four digits 

 present in all Pterodactyles from the Oolitic rocks, though Von 

 Meyer has said that the number of the phalangeal bones is variable 

 in those animals. The number is usually stated as 4, 4, 3, 2 ; which, 

 according to the interpretation of the hand just given, would read, 

 four bones in Digit II., four in Digit III., three in Digit IV., and 

 two in Digit V. So long as the Pterodactyle was supposed to be a 

 modified lizard it was not unnatural that the reverse reading should 

 be taken, and the increase in number of phalanges considered to be 

 in harmony with the lizard type, in which the phalanges from first 

 to fifth are 2, 3, 4, 5,3 ; while in the chameleon they run, from first to 

 fifth, 2, 3, 4, 4, 3. Thus, striking off the fifth digit of the cha- 



