OSTEOLOGY OF CARNIVOROUS DINOSAURS. 



139 



rior face above the articular end is more pronounced. Lull observes: "It in turn 

 differs from that of 'Z>. alius' in having no median fore and aft depression over its 

 articular face except a very slight one in front," 

 which is exactly the difference to be observed 

 between the Camptosaurus and Antrodemus meta- 

 tarsals. Furthermore, the articular face does not 

 extend as high up on the posterior as on the anterior 

 side — another Theropod characteristic — whereas in 

 Camptosaurus Trachodon, Thescelosaurus, and pre- 

 sumably also in Dnjosawus the two aspects are 

 about subequal. 



The principal measurements of metacarpal III 

 are as follows: 



771 m. 



Width of articular extremity 43 



Diameter, antero posteriorly 35. 5 



Width of shaft 75 mm. above end 29 



Greatest length of bone as preserved 1 39. 5 



The proximal phalanx of digit II ' is represented 

 by two bones, one slightly smaller than the other. 

 The larger of these, No. 5453, U.S.N.M., is prac- 

 tically the same size as the proximal phalanx of 

 digit II in the foot of Ornithomimus altus, which it 

 closely resembles in all details. Both of these bones, 

 Nos. 5453 and 6108, pertain to left feet. The former 

 is illustrated in two aspects in figure 73. Their 

 principal dimensions are as follows: 



Fig. 72. —Right met.\t.\ksal III of drnitho- 



SUMU.? AFFINIS, NEW SPECIES. COTYPE. NO. 



.'■16.S4, U.S.N.M. (.4), POSTERIOR view; (B) 



EXTERNAL VIEW. BOTH FIGURES h NAT. 



SIZE. Same bone as A. fig. 71, showing 



ADDITIONAL FRAGMENTS FITTED ON SINCE THAT 

 DRAWING WAS MADE. 



a 



Length, taken at center. . . 



Width of proximal end 



Width of distal end 



Least transverse diameter of 

 shaft 



No. 5453, 



U.S.N.M. 



mm. 

 82 

 34 

 31 



21 



No. 6108, 

 U.S.N.M. 



79 

 32 



20 



No. 5453, U.S.N.M., is one of the 

 cotypes of AUosaurus medius (fig. 73). 



The second phalanx (No. 5703, 

 U.S.N.M.) of digit III of the right hind 

 foot is shown in figure 74. This bone was 

 incorrectly identified by Lull as the 

 proximal phalanx of digit III. It is 

 slightly longer than the second phalanx 

 of Ornithomimus No. 5339, A. M. N. H. but otherwise resembles it in all partic- 

 ulars. This bone is to be distinguished at once from the proximal phalanx of digit III 



Fig. 73.— Pboximal phalanx of digit, II, Left, of Ornith- 

 omimus AFFiNis. C0TITE. No. 3453, U.S.N.M. (a) 



ANTERIOR view; (6) L.VTERAL VIEW. BOTH FIGURES i NAT. 



SIZE. (AFTER Lull.) 



1 Not digit rv as identified by Lull, in Maryland Report, p. 206. 



