56 PROF. H. G. SEELEY OUT A NEW 



ward, but soon become directed transversely outward, and retain 

 their upward direction. The facet for the head of the rib is at first 

 large, and at the base of the transverse process, and bounded poste- 

 riorly by the sharp ridge which runs below the transverse process 

 to the hinder margin of the neural arch ; but after a time the rib- 

 head rises higher, so as to be chiefly above the zygapophysial facet ; 

 and then it becomes smaller, the ridge behind it more or less dis- 

 appears or rounds away, and the transverse process, which was at 

 first triangular in section, becomes vertically compresed and thin. 



The interest of the series is in exhibiting the gradation of cha- 

 racters as the bones extend backward, though, as the surfaces are 

 invested with a thin argillaceous layer, and the bones have lost the 

 neural spines, there is still something to be desired in their con- 

 dition. 



In the 1st vertebra the anterior face of the centrum is flattened, 

 but somewhat concave, except towards the margin, which is convex. 

 The basal outline of the face is rounded, the sides are subparallel, 

 and the superior corners are rounded, while the neural canal is 

 concave. The median vertical measurement is 7'4 centim., the trans- 

 verse measurement nearly 7 centim. The measurements of the pos- 

 terior surface are slightly less ; but the articular face is more con- 

 cave, and its convex outer border is narrower. 



The sides of the centrum are concave from front to back, and 

 moderately convex from above downward, becoming closely approxi- 

 mate towards the base, so as to form a blunt basal ridge or keel, 

 which is most developed towards the anterior end : it is concave in 

 length. The transverse measurement in the middle of the centrum 

 below the neural arch, is 5*3 centim. 



The neural arch encloses a rather small neural canal, wnich is 

 not higher than wide. The z} r gapophysial facets are inclined at a 

 right angle, are 2| centim. broad, and parted below by an interspace 

 about 1 centim. wide. The external surfaces of the anterior zyga- 

 pophyses are oblique, extending, with a slight concavity, back to 

 the elevated border of the facet for the head of the rib, and extend- 

 ing concavely downward to form the pedicle, which joins the cen- 

 trum by an imperceptible suture. 



The facet for the head of the rib is large, vertically oval, less than 

 4 centim. deep, and 3| centim. wide ; it is deeply concave, in advance 

 of the middle of the side, 8 millim. below the anterior border of the 

 transverse process, which extends behind it, and above its posterior 

 half. These facets are not quite vertical, the transverse measure- 

 ment over their upper parts being more than the measurement at 

 the base. Below the base of this rib-facet there is a slight con- 

 vexity on the line of the neurocentral suture. 



The transverse processes are strong and directed upward and 

 outward, almost at the same angle as the zygapophysial facets, but 

 they are also directed a little backward. The superior surface is 

 flattened, smooth, looks inward and upward, 7 centim. wide at the 

 base, with the margins compressed and gently concave in length, 

 though the concavity is deeper on the posterior side, where it 



