NO. IGOU. OSTEOLOGY OF CAMPTOHAUJlUS—CilLMORE. 239 



The caudal rertehra'. — Thirty-three caudal vertebra^ were found 

 associated with Cat. No. 4282, U.S.N.M. Their position in the quarry 

 in relation to one another is clearly shown in Plate G. With the type 

 of C. 7i<mi(s (Cat. No. 2210, U.S.N.M.) Avere 34 caudals, most of them 

 still connected by the adhering matrix. After careful consideration 

 of the evidence presented by the above series, it is estimated that in 

 Cdjnptosaunis there would be at least 44 caudal vertebra? in the com- 

 plete tail. 



As found, there were interruptions (see Plate 0) in the anterior 

 series of No. 4282, but upon assembling the scattered parts it is be- 

 lieved they represent an unbroken string as far back as the sixteenth 

 caudal. Between the sixteenth (quarry number 208) and the distal 

 series (beginning with quarry number 235, see quarry map, Plate 6), 

 it is estimated there are five vertebra? missing. 



The above estimate is based not only upon the proportionate ratio 

 of decrease in size necessary' to fill the gap, but also upon the caudal 

 series of C. nan us ^ which has this region intact and still connected by 

 matrix. The terminal caudals are unknown, but the last one of the 

 series (estimated to be the thirty-eighth, quarry number 234) has a 

 transverse diameter on the posterior end of 13 mm. It is not likely 

 there was a series of rod-like caudals, as found in some members of 

 the Opisthocoelia," but rather that the tail ended more abruptly like 

 that of Stegosaurus, that is, with a pointed terminal caudal, as shown 

 by three specimens in the National Museum. 



In No. 4282, U.S.N.IM., the first caudal {sc, fig. 17), or, as it 

 might be better termed, sacro-caudal, is united to the sacrum by 

 suture, being more securely joined by the peg-and-notch articulation 

 (see fig. 17). It is considerably shortened antero-posteriorly, and, 

 viewed from the end, is cylindroid in outline. A heavy subcircular 

 rib, or transverse {tr, fig. 17), is attached by suture to the neural 

 process just above the neuro-central suture. The neural canal is con- 

 tracted to a small, circular passage having a diameter of 15 mm. On 

 the median ventral surface are tw^o subcircular depressions sepa- 

 rated by a median longitudinal ridge or keel. The neural arch is 

 much compressed transversely. The anterior zygapophyses are 

 placed quite close together, their articular faces being nearly vertical, 

 while the posterior are j^laced more obliquely and slightly overhang 

 the end of the centrum. The spinous process of this vertebra is miss- 

 ing. The second caudal bears the first chevron (see <"/., fig. 18). 

 Its centrum has a cupped anterior surface, the whole contour of this 

 end being concave dorso-ventrally. The posterior articulating sur- 

 face is more rounded, with an oblique ventral surface for the attach- 

 ment of the chevron. This end is only slightly concave on the 



<» J. W. Holland, Mem. Carnegie Mus., II, 1906, p. 2.53. 



