250 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. XXXVI. 



on the humerus of Iguanodon. The shaft is somewhat tM^kted and 

 planes passed through the longer axes of the articular ends would 

 cut one another at a slight angle. The outer surface of the radial 

 crest is roughened for muscular insertion. Below the crest the shaft 

 is constricted and is subcircular in cross section. The internal border 

 is regularly curved from end to end, Avhile the external is angularly 

 convex. The radial and ulnar condyles are Avell defined and posteri- 

 orly are separated by a broad, shallow depression Avhich -passes some- 

 what up the shaft of the bone. There is also a shallower depression 

 between them on the distal anterior surface of the bone. The articu- 

 lar ends of the humerus are quite rugose in the individual here 

 described. 



Measuremcnis of Specimen, Cat. No. .'/282, U.S.N.M. 



mm. 

 Greatest length of left humerus 3gQ 



Greatest width proximal end ^^q 



Greatest width dorsal end §2 



The ulna.— The ulna is heavy above and but little expanded on 



the distal end. Its 

 length slight^ ex- 

 ceeds that of the ra- 

 dius, but is shorter 

 than the humerus, 

 differing in the lat- 

 ter particular from 

 Trachodon, in Avhich 

 the ulna exceeds the 

 humerus in length. 

 There is the begin- 

 ning of a massive 

 olacrenon (see fig. 

 41), but it extends 

 but little above the 

 ^t f , ' '^"^ "^^^^^F ^^^B articular surface for 



MM ilMiil^^ ^^ ^^^ the humerus. Viewed 



proximally the end 

 is subtriangular in 

 outline. The middle 

 of the shaft in cross 

 section is elliptical. 

 The distal end is 

 somewhat expanded 

 (see w?, fig. 27), the 

 greatest diameter be- 

 ing transverse. The lower internal surface is slightly roughened and 

 flattened for contact with the gl•oo^■od external surface of the distal 



Pig. 27. — Right radils, ulka, and manus of Camp 

 tosaurus browni. holotype. cat. no. 4282, u.s.n.m. : 

 about i nat. size. front view. shows position 01 

 elements as found in the quarry. i, intermedium 1 



* rn, RADIUS ; //, ULNARE ; id, ulna. From a photograph 



