274 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. XXXVI. 



S4 (see fig. 37). The ventral surfaces of all the centra are flattened, 

 with a slight, median, longitudinal depression, which at once dis- 

 tinguishes them from the keeled or hsemally rounded sacral centra 

 of C brotvni. The ventral surface of the sacro-dorsal is regularly 

 and evenly rounded and is without the decided keel present in that 

 of C. hi'owni. 



The two spinous processes preserved (see Plate 13) rise as thick- 

 ened plate-like spines, the upper termination being thickened trans- 

 versely, especially on the anterior part of this end. The spine of 

 the sacro-dorsal is heavier anteriorly than the spine of sacral one, 

 and probably indicates the culmination in the development of the 

 spinous processes. The border below the thickened termination is 

 compressed and presents a sharp anterior edge. The posterior bor- 

 der is somewhat thickened and has a shallow, vertical groove which 

 may have received the sharp anterior edge of the spine posterior to 



Fig. 37. — (1) Lateral and (2) front views of first sacral centrum Camptosaurus 

 DisPAR Marsh. No. lS77a, Yale Museum. Paratype. J nat. size., a, anterior face 

 for articulation of first sacral rib ; h, posterior articulating surface for 



SECOND sacral RIB. (3) rOSTERIOR SACRAL VERTEBRA OF SAME. J NAT. SIZE. SHOW- 

 ING peg-and-notch articulation; top view: a, anterior end; p, postbriob end. 

 After Maesii. 



it, which would give the plate-like appearance of the three median 

 sacral sj^ines, as shown by Marsh in his first restoraton of G. tUspar. 



In No. 1878, Yale Museum, the ilium, pubis, and ischium are pre- 

 served, the two former elements being incomplete, that is, the ilium 

 lacks most of the preacetabular and postacetabular processes, and the 

 pubis most of the post-pubis, which, as shown in Plate 15, repro- 

 duced from a photograph of the specimens, has been restored in 

 plaster. 



In the jjelvic bones are found the chief differences which serve to 

 separate this species from the other members of the genus. The 

 ilium, in proportion to its length, is considerably deeper and more 

 robust than in any of the other species (compare figs. 29 and 30). 

 The preacetabular notch is wide and the acetabular notch deep. The 

 oblique border of the supero-posterior end is much longer — in most 

 individuals a third longer than in C. hrowni — and terminates pos- 

 teriorly as a thickened angular end. 



