40 Field Columbian Museum — Geology, Vol. II. 



ones forming the extreme tip of the tail; these must have been mere 

 nodules of bone, without processes. (See PI. X.) 



Several other vertebrae are assigned to the caudal series, chiefly 

 on the evidence of the venous foramina on the ventral side of the 

 centra, though they have no facets for the chevrons. Between these 

 and the continuous series, four vertebras have been intercalated; the 

 number may be too great; possibly not enough. That some were 

 missing is quite certain, since the change in the direction of the spine 

 is too abrupt in the ones preserved. Because the tail as restored 

 seems to be of about the length of some other known forms, I am 

 inclined to believe that the number of the caudal vertebrae, all told, 

 did not exceed twenty-five. All those preserved, except the anterior 

 ones, show a nearly circular and somewhat cupped surface on each 

 side for the attachment of the haemapophyses. The separate branches 

 are directed downward, outward and backward. They are somewhat 

 flattened and expanded distally, except the distal ones, which are 

 more rod-like. The diapophyses or ribs of the connected series 

 spring from near the middle of the centra dorso-ventrally, and are 

 directed outward horizontally, the most posterior ones also slightly 

 forward. They have a somewhat expanded extremity, with a cartilag- 

 inous margin. At the beginning of the series they arise near the 

 middle of the centra antero-posteriorly, but gradually approach the 

 anterior margin. They terminate as free ribs on the seventh before 

 the end, that is on the ninth or tenth before the extreme tip of the 

 the tail. The sixth has a small exogenous tubercle to represent the 

 process. None of the caudal vertebrae, save at the immediate base, 

 have functional zygapophyses, and the tail was evidently capable of 

 considerable lateral and vertical movements. There are no indications 

 whatever of a terminal fin, unless the upward curvature of the tip of 

 the tail suggests such an appendage. Its use, however, could not 

 have been great, since the evident shortness of the tail, and its inter- 

 ference with the hind limbs would have deprived it of much service 

 as a propelling organ. 



Pectoral Girdle. — The scapula is of the usual triradiate shape. 

 The coracoid or glenoid ramus is short and rather stout, some- 

 what expanded at the extremity, with the two articular facets 

 meeting in an obtuse angle, the larger, oval one for the glenoid 

 articulation ; the smaller, triangular one for union with the cora- 

 coid. The 'dorsal ramus is narrowest, is rather stout, thickened 

 on the posterior and thinned on the anterior border ; it termi- 

 nates in a flattened surface for attachment of a suprascapu- 



