OSTEOLOGY OF THE ARMORED DINOSAUEIA. 



71 



Both pertain to small, partly grown animals. These supplementary specimens show 

 very clearly the entire Stegoscmrus carpus, as may be seen by comparing figures 

 36 and 37. 



Professor Marsh recognized three elements in the proximal segment of the car- 

 pus and so indicated it in his restoration of 

 the skeleton. 1 Yet later in defining the genus 

 Diracodon 2 he observes that " in the fore foot 

 the intermedium and ulnar bones separate, 

 while in Stegosaurus these carpals are firmly 

 coossified," evidently overlooking the fact 

 that in plates 48 and 52 of the same article, 

 feet of the genus Stegosaurus are shown with 

 these elements separate. 



Eadiale (r.). — The radiale is much the 

 largest bone (see figs. 37 and 38, r) of the car- 

 pus and is opposed distally by metacarpals 

 I, II, and partly by III. ProximaHy it artic- 

 ulates exclusively with the radius. It is a 

 block-like bone, wider than long, with upper 

 and lower articulating surfaces roughened, the 

 former being flat, the latter rather angularly 

 convex transversely. The sides are vertical 

 with the exception of the posterior, which has 

 on its outer posterior half a rounded depres- 

 sion of some depth. The principal dimen- 

 sions of the radiale of an adult and a young 

 specimen are given below : 



Measurements of radiale 



Fig. 37.— Carpus (lacking pisiform) and portion of 

 right fore foot of stegosaurus sp. juvenile. 

 Cat.no. 7401, U.S.N. M. J nat. size. A, Front and 

 B, top views, in, Intermedium; r, radiale; ul, 

 ulnare; I, II, III, metacarpals one, two, ant» 



THUEE. 



- 



Juvenile, 

 No. 7401. 



Adult, No. 

 4937. 





mm. 

 72 

 62 

 50 



mm. 

 110 

 103 

 70 









Intermedium (in.). — The intermedium will be described from the young speci- 

 men bearing catalogue No. 7401. Viewed from above (in., fig. 37, B) this bone 

 is triangular in outline, the front forming the longest side. The anterior face is 

 shallowly concave dorso-ventrally, with an arterial foramen notching the external 

 border. In adult animals all traces of this notch are obliterated. 



The upper rugose surface is regularly convex transversely. It articulates with 

 the radiale and ulnare by straight, vertical ends. In an articulated foot it is sup- 

 ported in part by both metacarpals III and IV. Above it meets about equally the 

 distal ends of the radius and ulna. 



1 Amer. Joum. Sci., vol. 21, 1881, pt. 4, p. 170. 



3 Dinosaurs of North America, 1896, p. 193. 



