FAUNA OF THE GOSAU FORMATION. 



669 



from above; downward, and, though blunt anteriorly, is most com- 

 pressed on the right border. The articular surface is imperfectly 

 preserved, but was concave from above downward, straight trans- 

 versely, and inclined obliquely to both superior and inferior aspects. 

 The superior surface, which is slightly convex from side to side, 

 is margined on each side by a strong groove, which is not very 

 deep, and extends forward for more than half the length of the 

 bone. Between these grooves are a number of slight parallel 

 ridges. At the sides the bone is excavated for the attachment of 

 powerful ligaments, more so on the left side than on the right ; and 

 on the left side the irregular excavations extend further forward. 

 The under surface is comparatively flat, but concave in length, convex 

 from side to side, and marked in the middle with two irregular longi- 

 tudinal grooves, which have a tendency to branch as they pass forward. 

 These grooves are very imperfectly indicated in Biinzel's figure, which 

 gives no indication of their dendroid character. The posterior outline 

 of the bone is ovate, and less than 2 centim. deep. 



Dorsal Vertebra. 

 (See Biinzel, pi. i. figs. 24, 25.) 



A dorsal vertebra with the neural arch fairly well preserved is the 

 best vertebral evidence of this species (PI. XXX. fig. 5). The centrum is 

 4 centim. long, flattened on the under side, where it is 1-J centim. broad 

 in the middle, where most constricted ; it is concave from front to 

 back. The sides are compressed and somewhat concavely excavated 

 below the neural arch, where the least transverse width is 1\ centim. 

 Thus the body of the vertebra in section would be subquadrate. 

 The anterior articular surface of the centrum is concave, 32 milliin. 

 broad, and 27 millim. deep. The posterior end is not concave, but 

 somewhat flattened and convex from above downward. The margin 

 is a little worn ; the greatest transverse width is less than 3 centim., 

 the greatest depth 2\ centim. The neural arch is high, though not 

 unusually so for a Dinosaur. Its base is nearly as wide as the 

 anterior face of the centrum. It extends the whole length of the 

 centrum, and has the aspect of being compressed from side to side 

 below the transverse processes. The borders of the neural arch are 

 excavated (fig. 5), moderately in front, and more deeply behind, to 

 form the intervertebral passage for the nerves. The least length of 

 the neural arch from front to back, in the middle of the neural canal, 

 is 23 millim. The length from the anterior to the posterior zyga- 

 pophyses is about 5j centim. ; and the upper border of those facets 

 is fully that height from the base of the centrum. The anterior 

 zygapophyses are directed upward, forward, and inward. Their 

 external surface is rounded. There is a V-shaped notch between 

 them in front ; and they form the anterior' border of a transverse 

 cup-shaped depression in front of the neural spine, the hinder 

 borders of which cup are contributed to by the transverse pro- 

 cesses, which are directed upward and outward, and placed between 

 the zygapophyses in the middle region of the vertebra. The neural 



