272 PROCEEDINGS OF THE XATFOXAL MUSEUM. vol. xxxvi. 



While Marsh in the above description brings out most of the essen- 

 tial characteristics of this form, a recent examination of the type 

 specimen, combined with a study of additional material, shows that 

 several of the observations made at that time are not substantiated. 

 These remarks apply particularly to the description and figures of 

 the scapula and ilium, the latter, as will be shown later, being one 

 of the most characteristic elements of the skeleton. 



In a note published in the American Naturalist," Dr. S. W. Wil- 

 liston first called attention to the perpetuation of an error by Mr. 

 Richard Lydekker, who was struck with the great resemblance be- 

 tween the ilia (excepting the preacetabular portion) of Camptosaurus 

 dispar and I guanodon dawsoni. Doctor Williston says : 



The fact is that the figure of the former is wrong. The anterior portion of 

 the ilium of the type had been brol^en off and weathered, indications of which 

 are distinctly seen in the specimen. I'rofessor Marsh had this demonstrated 

 to him more than five years ago, and there are other ilia in the Yale Museum 

 in which this process is complete. 



I quite agree with Doctor AYilliston's observations with the excep- 

 tion that none of the ilia in the Yale Museum, so far as I could find, 

 show the complete preacetabular process, but there are other speci- 

 mens in the collection which have considerably more of the process 

 preserved than is shown in the ilium figured. That Marsh clearly 

 recognized the incorrectness of his first figure is evident, since in a 

 later jjaper ^ he rejiublished a figure of the pelvic bones of C. dispa?' 

 to the ilium of which had been added in outline a long, sharply- 

 pointed anterior process. That he was still in error is clearly shown 

 by the left ilium of C. dispar, Cat. No. 5473, U.S.N.M., which is termi- 

 nated anteriorly by a somewhat rounded spatulate end (see fig. 29). 



The incomplete scapula of the holotype was correctly figured on 

 Plate's, fig. 1, in the original description, but later '^ the scapula 

 and coracoid are represented as being complete. I am at a loss 

 to understand, however, upon what evidence Marsh based this res- 

 toration of the upper free extremity of the scapula, which is so 

 entirely different from all other scapulae pertaining to the members 

 of this genus. None of the ten or more scapulae examined by 

 me show anterior expansion of this end, but all agree, with slight 

 variations, in having the same general contour as the scapula of No. 

 4282, seen in fig. 23. I dwell on the correctness of the contour of 

 the type of C. dispar, from the fact that the specific characterization 

 of C nanus (see fig. 40) given by Marsh was based primarily upon 

 the differences in contour displayed by the scapulai of the two 

 specimens discussed here. 



« Amer. Nat.. XXIV, 1890, pp. 4.12-AlZ. 

 ^Amer. Journ. Sci., XLIV, 1S92, pi. v. 

 c Idem, XLVIII, 1804, pi. V. 



