260 



PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxvi. 



The femur is the most robust bone of the skeleton. It has a curved 

 shaft, and is compactly and strongly built throughout. The forward 

 arctuation of the shaft distinguishes this bone from all other known 

 American predentate dinosaurs excepting Laosaurus and Dryosau- 

 TU8. A compressed inner or fourth trochanter (7>, fig. 33) of the 

 pendant type is developed on the postero-internal margin of the shaft. 

 Dollo has called attention to this tyjDC of trochanter in Iguanodon 



as indicating a powerful caudo-femoral 

 musculature, as in some birds. In Camp- 

 fosaufvs, however, it appears more prom- 

 inently' developed than is found in any of 

 the European representatives of this group. 

 The fourth trochanter begins to develop 

 somewhat above the middle of the shaft, 

 the apex being directed downward and in- 

 ward toward the distal end of the bone. 

 Just anterior. to the trochanter is a shallow 

 vertical depression with a markedly rugose 

 surface which extends out on the internal 

 surface of the trochanter. The head (h, 

 fig. 33) is well developed and subglobular 

 in form, and is attached by a short, thick 

 neck at nearly a right angle to the main 

 axis of the shaft. The articular surface 

 of the head is somewhat rugose, and tliis 

 rugosity is continued along the superior 

 surface of the greater trochanter to its 

 external border. A prominent lesser tro- 

 chanter {a, fig. 33) rises on the antero- 

 external surface of the upper j^art of the 

 shaft, nearly to the height of the greater 

 trochanter, as a transversely compressed 

 blade. Posteriorly the lesser trochanter 

 is separated from the shaft by a deep, 

 narrow cleft. Behind the head is a pro- 

 nounced groove separated from a second 

 concave depression on the posterior median 

 surface of the shaft by a heavy, rounded, longitudinal swelling. The 

 superior surface' of the greater trochanter (2, fig. 42) is wider and 

 more gently rounded antero-posteriorly than the head. The distal 

 end has the usual condyle shape, though the inner condyle {c, fig. 33) 

 is much more robust than the outer. The two condyles are separated 

 by a deep, intercondylar groove, wider at the bottom than the top. 

 Both condyles project decidedly backward. The anterior inter- 

 condylar groove (2, fig. 42) is wide and of moderate depth, con- 



FlG. 33. RiGUT FEMUR OF 



CAMPTOSADRUS D I S P a U 



Maksh. Cat. No. 5818, 

 u.s.n.m. ; i nat. size. 

 Inner view, a, lesser 



TROCHANTER ; I), INNER TRO- 

 CHANTER ; C, INNER CON- 

 DYLE ; h, HEAD. From a 

 PHOTOGRAPH. 



