148 REVISION OF THE PEI.YCOSAURIA. 



inclined somewhat to the rear. The first pair of processes is only a short distance 

 above the centrum ; through the mid-dorsal region the first pair rise at this level, but 

 in the posterior dorsal and lumbar regions they rise from farther and farther up on 



the spine. 



The ninth vertebra : The centrum is elongate with nearly round articular faces 

 and wide notochordal funnel. The anterior face does not have a wide intercentral 

 face below, but on the middle of each side the edge is widened by a sharp angulation, 

 marking the point where the rib-head passes between the centra to articulate with the 

 intercentrum. The sides of the centra are pinched in somewhat below the noto- 

 chordal canal, constricting the lower portion into a broad obtuse ridge, which, how- 

 ever, in no wise resembles the sharp, thin keel of the cervicals and anterior dorsals of 

 Dimetj'odon. The neurocentral suture is closed, but still clearly visible. The trans- 

 verse process rises far up on the neural arch, almost directly below the anterior zyga- 

 pophysis. The anterior zygapophyses have nearly horizontal faces, but they look a 

 little in as well as up. The posterior zygapophyses rise from high up on the spiue, 

 well above the line of the anterior zygapophyses. This is a very distinctive character 

 through the whole column. The spine shows the same characters as that of the 

 seventh vertebra ; there are four pairs of processes and then four on one side and three 

 on the other. The lower pair stood straight out from the spine, but are broken away. 

 The apex of the spine is clavate and beut to the rear, but it is not so wide as on the 

 seventh. 



The tenth vertebra {first dorsal) has the same form as the eighth. The centrum 

 is broken and the posterior end lost. The transverse process springs from the base of 

 the anterior zygapophysis as much as from the neural arch ; a strong supporting pro- 

 cess extends from the base down toward the centrum. This origin of the transverse 

 process seems to be peculiar to the genus ; it occurs in none of the ClepsydropincB 

 or the Theropleitridce. The spine is as in the seventh and eighth vertebrae ; the pro- 

 cesses of the first pair are opposite, the others alternate ; there are eight on each side. 

 The apex of the spine is still clavate, but ver)- much narrower than in the preceding 

 vertebra ; the top is marked by a shallow but well-defined circular pit. 



The eleventh resembles the preceding one very closely. The anterior face of the 

 centrum is broken, but the edge of the posterior face shows the expansion of the edge 

 of the side marking the position of the capitulum of the rib. The transverse process 

 is located well up on the base of the anterior zygapophysis with a strong supporting 

 ridge below reaching well down onto the centrum. The first pair of processes is per- 

 fectly preserv'ed ; they stand out almost straight from the side of the spine and the 

 ends are expanded into rugose knobs. The apex of the spine is thin, but hardly 

 expanded antero-posteriorly ; the processes above the first pair are much shorter, but 

 are not reduced in size as they go up the spine, so that one process uear the top is 

 longer and stronger than any below except the first pair. 



The tivelfth has the centrum broken, but the transverse process of the left side is 

 perfectly preserved. This stands so far forward and is so thoroughly incorporated with 

 the anterior zygapophysis that it is impossible to say whether the transverse process 

 stands out from the anterior zygapophysis or the anterior zygapoplnsis from the trans- 

 verse process. The supporting ridge below runs down to the centnnn, but does uot 

 fuse with it, being separated from it by a sharp notch at the lower end. The trans- 

 verse process runs straight out or even slants a little forward, so that it lies almost 



