[parks] new species OF TRACHODONT DINOSAUR 57 



The radius is a more slender bone than the ulna, cylindrical and 

 gently expanding towards the distal end; proximally the expansion 

 is more rapid to the edges of the articular facette. This bone was 

 split longitudinally in the process of removal and the separated parts 

 warped; in consequence, the swelling in the middle, as shown in the 

 figures, is to be disregarded. 



Measurements of Radius mm. 



Total length 555 



Minimum girth 140 



Proximal end, transverse (obliquely inwards and back) 83 



Proximal end, transverse (obliquely inwards and forward) 60 



Distal end, transverse (obliquely inwards and back) 70 



Distal end, transverse (obliquely inwards and forward) 50 



The carpals are apparently two: one is an irregularly triangular 

 bone with a greatest edge of 40 mm. situated anteriorly, below the 

 radius on the side towards the ulna. The other carpal is a much 

 smaller, disc-like bone of a diameter of 28 mm. This bone was found 

 on the posterior side directly behind and below the ulna. These bones 

 are shown in Figures 8 and 9; the larger bone is almost certainly in 

 place; the position of the smaller carpal is less certain and does not 

 correspond with the relationship given by Brown for the typical 

 trachodont. 



The greatest interest attaches to the manus, every bone of which 

 is excellently preserved. An anterior view of the bones, almost ex- 

 actly in the position in which they lay in the matrix, is shown in 

 Figure 10, and a posterior view in Figure 11. The relationship of 

 these bones to the radius and ulna, in both this foot and on the right 

 side, confirms the conclusions of Brown^ and disproves Marsh's 

 original arrangement. 



There are four metacarpals, which, according to Brown, are to 

 be considered as II, III, IV, and V. Metacarpals III and IV are very 

 closely associated, II is somewhat less closely associated with III, 

 and V is quite free and divergent. 



Metacarpal II is a fairly straight bone, swollen in the middle, 

 flattened proximally, and not so much distally, and with the outer 

 side (towards axis of foot) flattened, more particularly distally, as if in 

 close contact with metacarpal III. Length 185 mm. Metacarpal 

 III is a much heavier bone, slightly twisted, flattened externally at 



I The Manus in the Family Trachodontidae, Barnum Brown, Bull. Am. Mus. 

 Nat. Hist., Vol. XXXI, Art. X, 1912. 



Sec. IV, Sig. ,S 



