NORTH AMERICA AND THEIR VERTEBRATE FAUNA. l6l 



were as thick as the centra and resembled them very strongly. There are a 

 large number of separate disks without neural arches, which are indistinguish- 

 able otherwise from the arch-bearing centra. They have a strong scar upon 

 the upper surface, to all appearances identical with the scar which would 

 appear upon the upper surface of the centra if the arch were removed. The 

 presence of the scar is explained by the fact that the anterior edge of the 

 neural arch extends far anterior to the edge of the centrum and in many of 

 the vertebrae fits accurately into the scar mentioned. The original statement 

 by Cope that the neviral arches were not anchylosed to the centra is erro- 

 neous, as already shown by Case, and in the present collection there is no 

 evidence that the arches were loosely attached, nor was a single separate 

 netu"al arch collected. 



A most striking feature in several of the vertebra is the presence of a 

 distinct canal, running lengthwise through the neural arch above the neural 

 canal. This is clearly shown in at least five vertebra, where it has been 

 worked out, and is indicated in several others, where it is occluded by the 

 compression of the specimen. In one vertebra, apparently an anterior dorsal, 

 the canal — supraneural canal as it may be called — is higher than wide and 

 separated from the neural canal by a considerable thickness of bone. The 

 upper part of the arch is broken away, so that the exact dimensions of the 

 opening can not be given (plate 22, fig. i). Two other vertebrae from appar- 

 ently farther back in the series show similar canals. In one with the spine 

 complete the canal is more nearly circular and the partition between it and 

 the lower canal is very thin and has been in part destroyed by decay. In 

 one of the larger anterior dorsals the canal is complete, but its upper two- 

 thirds appears to be divided vertically by a narrow partition. 



The supraneural canal seems to be most perfect in the vertebra with 

 prominent transverse processes, regarded as anterior dorsals. Here it is 

 narrow, but of considerable vertical extent, and is either complete or inter- 

 rupted in a part of its aperture by a vertical partition. In the vertebras with 

 short transverse processes (anterior dorsals ?) , the canal is small and circular, 

 or the neural arch is imperforate but marked by very deep pits extending 

 inwards in the position of the canal. In the sacrals deep pits are present, 

 but the arch is imperforate. It is probable that this canal lodged a strong 

 ligament which was in some parts of the column continuous and in others 

 present in segments between the vertebrae. 



Pelvis. — There are two perfect and two imperfect ilia which are provision- 

 ally assigned to the genus Cricotus. They differ from any known form of ilia 

 from the Texas beds in possessing a long, thin process which starts from the 

 middle of the posterior side of the crest and extends obliquely backward and 

 upward. The sides of the process are fiat and nearly parallel and the narrow 

 terminal face evidently bore a cartilaginous extension. The lower portion of 

 the bone is rather long proportionately and the cotylus is shallow. The articu- 

 lar faces for the pubis and ischium are rather thick (plate 22, figs. 2 and 3). 



