372 Annals of the Carnegie Museum. 



The proximal phalanx of the second digit is much the largest of 

 the entire series. The proximal articular surface is flat and circular in 

 outline, the vertical and lateral diameter of this end of the bone being 

 equal. Distally this phalanx is much depressed and greatly expanded 

 transversely. The distal articular surface is very broad but shallow 

 and divided by a deep, median, vertical groove into two subequal 

 lateral moieties with smooth convexly rounded surfaces. This 

 phalanx, as well as its metacarpal, has been erroneously con- 

 sidered as belonging to the third instead of second digit of the 

 series by Professor Osborn, as will readily appear by a reference 

 to fig. 7 of that author's paper on the " Fore and Hind Limbs 

 of Carnivorous and Herbivorous Dinosaurs," published as Article 

 XI. of Vol. XII. of the Bulletins of the American Museum of 

 Natural History. 



The proximal phalanx of the third digit is short, very much depressed, 

 more especially at the distal end, and expanded laterally. The proxi- 

 mal articular surface is elliptical in outline, slightly concave, with its 

 transverse diameter about double that of the vertical. The distal 

 articular surface is broad, but extremely shallow. There is a broad 

 but very shallow depression in the middle, faintly dividing it into two 

 ill-defined articular areas. The bone is of about equal transverse 

 dimensions throughout its length. 



The proximal phalanx of the fourth digit is short and stout, much 

 narrower than that of the third, but not so depressed. Seen from above 

 it appears somewhat wedge-shaped, the length of the external lateral 

 border greatly exceeds that of the internal. The proximal articular 

 surface is slightly concave and semicircular in outline. The distal end 

 is depressed, with an ill-defined articular surface crossed by a shallow, 

 median vertical groove. 



The proximal phalanx of the fifth digit is more massive than that of 

 either the third or fourth, but smaller than the corresponding bones of 

 digits one and two. Seen from above, it presents a broadly wedge- 

 shaped superior surface with an extended external lateral margin, 

 while the inner margin is reduced to a sharp ridge where the proximal 

 and distal surfaces converge and meet at an acute angle. The bone is 

 broader and less depressed than either of the two elements last de- 

 scribed. The proximal articular surface is irregularly quadrangular 

 in outline, the transverse dimension about double the vertical. Dis- 

 tally there is a poorly defined articular surface. 



