1887.J On Parieasaurus bombidens {Owen). 339 



The vertebral column comprises 29 vertebra?, of which 18 are pre- 

 sacral, 2 sacral, and 9 caudal, though a few caudal vertebrae may 

 possibly be missing. Crescentic intervertebral wedge-bones are 

 developed between most of the vertebrae. The ribs all articulate by 

 double heads. In the cervical region both facets are on the centrum, 

 and the ribs have long forks for the head and tubercle, which are of a 

 Crocodilian character. The neural arch is depressed and expanded, 

 and the neural canal small. The centrum is comparatively long ; and 

 the cervical vertebrae pass into the dorsal series in the same way as in 

 Plesiosaurs. 



The dorsal vertebrae are nine in number. The parapophyses are 

 somewhat elongated ; and the diapophysis forms a transverse process 

 which is only separated from the post-zygapophysial ridge by a notch. 

 The neural spine is a short inverted cone nearly as wide at the summit 

 as it is high. The neural arch is nearly three times as wide as the 

 centrum is long. 



The dorsal ribs are in natural contact with the vertebrae ; they are 

 strong, expanded vertically at the proximal ends, and directed hori- 

 zontally outward before they curve backward. In the last dorsal the 

 parapophysis is very small. The ribs closely resemble those of 

 Crocodiles and Labyrinthodonts. There is one lumbar vertebra with 

 long transverse processes. 



Two vertebrae are anchylosed together in the sacral region, but the 

 second does not differ in form from the early caudal, and the pelvis 

 is supported by the first vertebra of the sacrum. The sacral rib 

 has a massive development so as to extend along much of the 

 length of the ilium : this rib is compared to that of the great Sala- 

 manders. The same mode of support for the pelvis is found among 

 the Anomodontia. The ilium has a mammalian form and position, 

 lying almost entirely in advance of the acetabulum ; but there is no 

 close correspondence in form with any mammalian genus. 



The caudal vertebrae rapidly diminish in size, and show no trace of 

 a notochordal condition. The neural arch is reduced in width. Small 

 caudal ribs were developed. 



The form of the neural spine in the vertebral column is suggestive 

 of the recent Japanese Salamander, but as a whole the vertebral 

 column has nothing in common with existing Amphibians. 



The interclavicle and clavicles form an anterior bow, like that seen 

 in Nothosaurians, toward which the clavicular arch of the Ich- 

 thyosaurian genus Ophthalmosaurus approximates in the mode of 

 union of the bones. The interclavicle is a symmetrical /\ -shaped 

 bone with its limbs diverging, and directed backward. The scapular 

 arch is very massive, and appears to include coracoid and scapula. 



The only remains of dorsal armour preserved consist of relatively 

 small and scattered bony scutes. 



