THE WING-FINGER OF PTERODACTYLS 



701 



2, 3, 4, 4, to which there are probably few or no exceptions. The 

 first three of these agree absolutely with the normal and primitive 

 formula of the first three digits. The fourth pterodactyl finger has 



Fig. 3. — Right front leg of Ophiacodon Marsh, a theromorph reptile from the 

 Permian of New Mexico. Two-thirds natural size. 



