276 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxvi. 



on Metacarpal II and is not visible from the front view as in the 

 foot of Cat. No. 4277, U.S.N.M. (see fig. 28). In other respects the 

 foot does not differ materially from the description already given in 

 that part of the present paper devoted to the osteology of Campto- 

 saurus. 



The restoration (see Plate 18) of Camptosaurus dispar published 

 by Marsh * was based on the typical specimens, and while it depicts 

 well the general appearance of the animal, it is now known to be 

 erroneous in the following particulars: The thoracic region is too 

 long by at least three, and possibly five, vertebrae; all of the presa- 

 cral vertebra? are rib-bearing, and thus there are no true lumbars; 

 the anterior caudal vertebra?, as shown in the restoration, have the 

 arches and transverse processes too high above the centra, the latter, 

 as shown in fig. 18, being below the level of the pre- and postzygapo- 

 physes. The spines should also be more inclined backward and de- 

 crease more rapidly in height posteriorly ; the transverse processes 

 are continued too far posteriorly, as shown by two specimens in the 

 National Museum, where they end on either the twelfth or thirteenth 

 from the sacrum. Other minor corrections have been touched upon 

 in the previous pages, so need no mention here. 



As shown by the skeleton, C. dispa?' is an animal of quite robust 

 proportions, only exceeded in size by O. amplus. Marsh estimated its 

 length as being 20 feet. 



After a review of the typical specimens as compared w^ith the other 

 species of the genus, C. dispar may now be distinguished by the fol- 

 lowing characters : . 



Specific characters. — Typically of large size. Cervical centra with 

 heavy heel. Foiir sacrals with peg -and -notch articulation. Sacral 

 centra flattened inferiorly. Sacra-dorsal without ventral heel. Ilium, 

 deep., and heavy in its proportions. Ischium stout., tinth greatly en- 

 larged distal extremity. Ungual of Digit I of pes rounded and 

 pointed. 



CAMPTOSAURUS AMPLUS Marsh. 



Camptonotus amplus Marsh, Amer. Jouni. Sci. (3), XYIII, 1879, p. 503. 

 Camptosaurus amplus Marsh, Amor. Journ. Sci. (3), XXIX, 18S5, p. 169; 



16th Ann. Rep. U. S. Geol. Snrv., 1894-95, Pt. 1, 1896, p. 196. 

 Vamptosaurus amplus Nopcsa, Foldtani Kozlony, Budapest, XXXI, 1901, 



p. 210. 

 Camptosaurus amplus Hay, Bull. No. 179, U. S. Geol. Surv., 1902, p. 501. 



Holotype. — No. 1879, Yale University Museum, was collected by 

 Mr. Arthur Lakes from "Big Canyon Quarry," Jurassic (Morrison 

 Beds), in the vicinity of Como, Albany County, Wyoming. It con- 

 sists of a right pes nearly entire. The first description is as follows: 



A second species of this genus, about three times as large as the one [C. dis- 

 part just described, is represented by various remains, among which is a li'ft 



« Amer. Journ. Sci., XLVII, 1894, pi. vi. 



