Merriam.] 



Triassic Ichth yopterygia . 



107 



Chonespondylus, by Leidy. There is, however, nothing to indicate 

 that it represents a group distinct from Cymbospondylus. So 

 far as can be determined from the fragmentary type specimen, 

 this species has combined in it the length of vertebra found 

 in C. piscosus and the peculiar flaring articular funnels of 

 C. petrinus. The animal from which this vertebra came was 

 very much larger than that indicated by the types of piscosus 

 and petrinus. 



MEASUREMENTS OF TYPE SPECIMEN. 



Estimated height of centrum 120 mm 



Estimated width of centrnm 84 



Length of centrum 58 



AFFINITIES OF CYMBOSPONDYLUS. 



So far as can be determined with the material at hand, 

 Cymbospondylus is closely related to Shastasaurus, having 

 the peculiar form of rib articulation which has been described 

 for that genns, and it is possible that it will be shown later 

 that the two are identical. The species which we now have, 

 differ from Shastasaurus in possessing much broader and 

 heavier diapophyses, the lower ends of which are continuous 

 with the anterior margin . In the well preserved upper arches of 

 C. piscosus the spines are relatively thin, there is no trace of a 

 lateral rib, the zygapophyses stand more nearly at a right angle 

 to the axis of the spine than in Shastasaurus, and the whole 

 arch comes nearer to an erect position than in the anterior 

 dorsal region of that genus. With the material available, it is 

 advisable to keep the older Cymbospondylus type distinct from 

 the Shastasaurus group of the Upper Triassic. Later discoveries 

 may show that they cannot be separated genetically, or may 

 bring out differences much more important than those indicated 

 in the specimens now known. 



POSTSCRIPT. 



After the description of Cymbospondylus was partly printed, a good collec - 

 tion of saurian material was obtained from the middle Triassic of Nevada. 

 The bones are all embedded in blocks of very hard limestone, from which 

 it will require many months of careful work to free them. At the present 

 time little more can be determined than that several specimens, which 

 appear to belong to C. petrinus, show a number of peculiar characters not 

 heretofore noticed in any of the forms which have been examined. The 

 results of a study of this material will appear in a later paper. 



