FAUNA OF THE GOSAU FORMATION. 



647 



posteriorly. The neural canal is high and narrow : the sides of the 

 neural arch converge upward ; and the anterior zygapophyses have 

 the facets looking inward ; they are concave in depth. 



The second and third vertebrae of the series only differ in having 

 slight tubercles adjoining the anterior and posterior articular margins 

 on the middle of the sides, and in the decreasing dimensions of the 

 centrum and processes, though the length still remains the same. 

 The fourth vertebra is distorted by vertical compression, and the 

 fifth by lateral compression. It, however, has the neural arch well 

 preserved, and shows the length from the anterior to the posterior 

 zygapophyses to be inches. There is also an indication of a slight 

 neural spine broken away, which rose above the posterior zygapo- 

 physes. The greater part of both anterior and posterior facets pro- 

 jects beyond the centrum. The anterior pair of facets is divided 

 from each other ; but there is only a slight notch at the hinder ex- 

 tremity of the posterior pair. In the sixth vertebra the neural 

 arch is seen to taper posteriorly, when seen from above, in a trian- 

 gular outline slightly compressed in the middle ; and in the seventh, 

 in which the centrum is inch long, 1 T 4 F inch deep posteriorly, 

 and slightly wider, the neural arch is 2 T \ inches long. There is a 

 distinct concave compression below the anterior zygapophyses, from 

 which faint ridges extend backward longitudinally towards the pos- 

 terior zygapophyses. The facet from which the transverse process 

 has come away is still ovate, about j 7 ^ inch long, and is placed in the 

 middle of the side of the centrum, just below the neural arch. The 

 neural spine is seen to be a slight sharp ridge. The anterior zyga- 

 pophyses are inch apart, while the posterior zygapophyses, which 

 have smaller facets, are inch long. The groove on the base of the 

 centrum has become somewhat narrower and more sharply denned. 

 Here several vertebrae appear to be missing ; and in the next of the 

 series the transverse process has become much smaller, is placed lower 

 on the side of the centrum, is margined by a vascular groove in front, 

 and is prolonged backward by a sharp ridge towards the articular 

 margin. The vertebrae now begin to elongate a little ; and the ninth 

 of the caudal series is 1 T 9 ^- inch long ; the transverse processes have 

 disappeared, and are only marked by a sharp median ridge in the 

 middle of the centrum, margined in front by an oblique vascular 

 groove. Above these lateral ridges the centrum is compressed from 

 side to side ; the basal groove has become much shallower and 

 best marked towards the extremities. The tenth and eleventh show 

 the neural arch to be greatly compressed from side to side, and to 

 rise very much higher behind than in front, owing to the greatly 

 diminished size of the anterior zygapophyses. The posterior zyga- 

 pophyses have disappeared; and the centrum is a good deal constricted 

 in the middle. The twelfth centrum shows a much greater reduc- 

 tion in size of the neural arch, which leaves the posterior third of the 

 centrum free. The underside of the centrum is similarly compressed 

 to the upper part, though the median basal ridges become rounded. 

 The facets for the zygapophyses are distinctly marked at both end=, 

 and divided by a groove, of which there is no trace in the middle of 



