512 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 49, 



the first it is directed downward and backward. A comparison of 

 this foot with the manus recently described by Lambe ^ leads me to 

 believe that the digit designated by him as the second is reaUy the 

 first. This is indicated by the shortness of met. I, and especially by 

 the phalangial formula. In all associated fore feet of Theropodous 

 dinosaurs as shown in the accompanying table, there are two pha- 

 langes on the first digit with a progressive increase to the point 

 where some of the lateral toes have commenced to degenerate. The 

 lengthening of the penultimate phalanges appears peculiar to Thero- 

 podous dinosaurs and is a mechanical development for the more 

 perfect use of the talons of the fore feet. The principal measure- 

 ments of the bones of the manus are shown in the following table : 



Measurements of Fore-Foot Elements. 

 Metacarpals. 



Phalanges. 



Phalangial Formulae op Various Theropods. 



1 The Ottawa Naturalist, vol. 27, 1914, pp. 219-131, pi. 13. 



