81 



posterior or down-looking are confluent, and scarcely separated by an emar- 

 gi nation. 



The neural spines, at their bases, have a slight posterior obliquity; and the 

 superior portions lean strongly in the anterior direction. The inferior limbs 

 of the cervical pleurapophyses appear to be entirely wanting. The articular 

 faces for the chevron-bones are seen at the extremity of the inferior rib of the 

 caudal. 



Of the cervicals, there are both axis and atlas. Of the caudal series, 

 probably the distal half, at least, is lost. A single vertebra near the middle 

 does not relate to either of those anterior or posterior to it. There axe, there- 

 fore, at least four lost from that region also. 



There is a considerable interruption immediately anterior to the last 

 dorsal vertebra. Three large vertebrae, with long diapophyses belonging 

 here, were embedded in the hard matrix which protected the pelvic arch. 

 These are far from relating immediately to the vertebrae preserved before and 

 behind them. I estimate the number missing as follows: Seven of the four- 

 teen dorsals preserved have more or less elongate diapophyses. In Plesio- 

 auri, vertebrae of this character are much more numerous; in P. homalospon- 

 dylus, Owen gives seventeen. If we add ten to the series in the present 

 species, it will give the abdominal space between the adjacent margins of 

 the oo. 2?ubis and coracoidea an extent equal to the length of the pelvic arch. 

 This is relatively shorter than in the Plesiosaari. Dr. Turner found that a 

 space of "three or four" feet intervened between the two portions of the 

 skeleton, which was otherwise continuous. I think ten an average number 

 to represent safely the missing dorsals. 



From the cervical proximal regions, probably three vertebrae are missing 

 from two interruptions. The remainder of the cervical series exhibits three 

 interruptions. Most of the proximals have been broken medially, leaving 

 the articulations solid, an advantage in determining their continuity. Three 

 vertebrae and one-half are thus found missing in this region. 



The whole number of vertebrae preserved and lost, with the relative 

 lengths of each, may be stated as follows : 

 11 c 



