71 



cave at the upper part : these surfaces disappear in the anterior processes of 

 the eleventh and succeeding vertebrae. The upper part of the neural arch * is 

 quadrate, narrower posteriorly, and by the contraction of this part in the tenth 

 and succeeding vertebrae taking on a triangular form, it is incomplete and open 

 in the eighteenth vertebra. The spinous process rises from the whole antero- 

 posterior extent of the middle line of the neural arch, which is concave on each 

 side of its base. 



The under surface of the bodies of all but the small terminal caudal vertebrae 

 is quadrate and concave, with each of the four angles produced into an articular 

 process! : the first caudal vertebra is distinguished by having only the two poste- 

 rior angles so modified. To these and to the anterior articular angles of the 

 second vertebra the separate haemapophyses of the first caudal are articulated. 

 These are rather irregular styliform processes, with the articular base extended 

 in the antero-posterior direction, and having two articular surfaces! for junc- 

 tion with the angles of the adjoining vertebra. The second and succeeding pairs 

 of haemapophyses have a broader base, with a rough process projecting inwards 

 from the interspace of the two terminal articular surfaces : they are compressed 

 and lameUiforra, and the spine developed from their anchylosed ends is strong, 

 compressed, and with a thick rugged extremity. The spine of the sixth, though 

 shorter than the preceding ones, has a greater antero-posterior extent. A tu- 

 bercle, developed on each side near the extremity of the second and third haemal 

 spines, is represented by a ridge situated nearer the base in the succeeding ones 

 as far as the eighth ; in this and the succeeding spines the ridge is continued 

 into a process projecting from the posterior margin of the hsemapophyis. The 

 canal formed by the confluent haemapophyses and intervertebral space for the 

 caudal prolongation of the aorta, extends from the second to the seventeenth 

 vertebrae ; beyond this a groove is continued, formed by the interspace of the 

 two anterior inferior tubercles of the centrum. In the first and second caudal 

 vertebrae a groove is continued from the middle of the lower angle of the cen- 

 trum on each side obliquely backwards to the posterior margin of the transverse 

 process, and thence, indenting the posterior part of the base of the neurapophysis, 

 to the spinal canal. This groove plainly indicates the spinal or vertebral artery 



* PI. VIII. fig. 7. t Fig. 8. : Fig. 5. a and b. 



