NO. 1666. 



OSThJOLOGY OF CAMPTOi^AVRVS^aiLMORE. 



281 



rather than those of C. dispar. The opisthocoelian nature of the an- 

 terior vertebrae is not so pronounced as in the hirger species. 



The dorsal series, though all are not articulated, appears to be com- 

 plete, consisting of IG vertebra-, many of which lack parts of their 

 processes. The only marked characters in the dorsals of ('. nanus 

 are to be seen in the spinous processes of the posterior portion of the 

 series, which are comparatively thin and lack the enlarged upper ex- 

 tremities of the same vertebrae in C. dispar and C. hrowni The arches 

 also appear to be relatively higher, with a corresponding enlarge- 

 ment of the neural canal, in this respect approaching C. prestwkhlL 

 The sides of the centra (considered as a whole) are less concave in the 

 longitudinal direction and appear to be more evenly rounded ven- 

 tralh^ The centra gradually increase in length from the first to the 

 thirteenth, the four- 

 teenth being the shortest .•?- t — , 3 



of the posterior dorsals 

 (26 mm.). The fifteenth 

 and sixteenth dorsals 

 may be distinguished 

 from the others by the 

 enlargement of their 

 posterior ends in adap- 

 tation to the correspond- 

 ing surfaces of the 

 centra with which they 

 articulate. The six- 

 teenth or sacro-dorsal 

 (see S. dor., fig, 39) is 

 suturally united with 

 the centrum of the first 

 sacral. Its ventral sur- 



s. dov. 



Fig. .39. — Sacku.m of C.vMrTOSAUKUs nanus Maksh. 

 Cat. No. 2210, U.S.N.M. \ nat. size. Holotype. 

 Viewed from the right side. a. zyg., pkezyga- 

 popHYSES ; art. s., articular surface for first 

 sacral rib ; il., ilium ; o. t., ossified tendons ; p., 

 i'arapophysis of the fifteenth dorsal ; p. il., 

 preacetabular process of ilium ; p. zy<j., postzyga- 

 I'OPHYSEs ; S^, 8", 8% 8*, sacrals one to four, 

 respectively ; tr., transverse process or dia- 



POPHYSIS; 1, spine of FIFTEENTH DORSAL; 2, SPINE 

 OF SIXTEENTH OR SACRO-DORSAL ; 3, -), AND B, SPINES OF 

 SACRALS ONE, TWO, AND THREE. 



face lacks the decided 

 keel found in the sacro-dorsal of C. hrowni. The more detailed 

 description of this vertebrae and the succeeding sacrals will be found 

 in that part of the present paper relating to the osteology of Camp- 

 tosaurus^ pages 242 to 244. The sacral vertebrae show the most distinc- 

 tive character of the species in the ab.sence of the peculiar peg-and- 

 notch articulation of the centra, which forms an important feature of 

 the larger species. By some this difference might be considered of 

 more than specific importance, but on account of the close similarity 

 (except in size) of nearly all of the other elements to the homolo- 

 gous parts of the larger species, and the lack of other diagnostic 

 characters, I can see no reason for separating this form generically. 

 It is of interest to note the similarity in this respect of C. nanus to 

 C. prestwichii as described and figured by Hulke (see fig. 43). 



