0. C. Marsh — New Genus of Sauropoda. 



91 



ponding vertebrae of Morosaurus, and have a very long, deep 

 cavity in each side of the centrum, to which the proposed gen- 

 eric name refers. All the trunk vertebrae hitherto found are 

 proportionately nearly double the length of the corresponding 

 centra of Morosaurus, and the lateral cavity is still more elon- 

 gate. These points are shown in the posterior dorsal vertebra 

 represented in figures 1 and 2. The neural arch in this region 

 is lightened by cavities, and is connected with that of the 

 adjoining vertebrae by the diplosphenal articulation. 



The sacral vertebras in Pleuroccelus are solid, as in Morosau- 

 rus, but much more elongate. The surface for the rib, or 

 process which abuts against the ilium, is well in front, more so 

 than in any of the known Sauropoda. Behind this articu- 

 lar surface, is a deep pit, which somewhat lightens the cen- 

 trum. These characters are seen in the sacral vertebra repre- 

 sented in fio;ures 3 and 4. 



Fig. 



Pig. 4. 



Figure 3. Sacral vertebra of Pleuroccelus nanus, Marsh ; side view. 

 Figure 4. The same vertebra ; posterior view. 



Both figures are one-half natural size. 



The first caudal vertebra has the centrum very short, and 

 its two articular faces nearly flat, instead of having the an- 

 terior surface deeply concave, as in the other known Sauro- 

 poda. The neural spines in this region are compressed trans- 

 versely. The middle and distal caudals are comparatively 

 short, and the former have the neural arch on the front half 

 of the centrum, as shown in figures 5 and 6. 



-Fig. 5. Fig. 6. 



Figure 5. Caudal vertebra of Pleuroccelus nanus, Marsh ; 

 Figure 6. The same vertebra ; superior view. 



Both figures are one-half natural size. 



side view. 



