148 Prof. H. G. Seeley on 



to PalcBOsaurus. The vertebvee already figured are indicated 

 by the numbers 17, 18, 19, 25, 27, and 38. The new 

 materials show that the caudal vertebra steadily decrease in 

 length as they diminish in size, and that the neural spine is 

 inclined backward, and finally disappears, though the zyga- 

 pophyses persist in the smallest vertebree preserved. 



Fig. 1. 



A dorsal rib of Palceosaurus, sbowinf»' capitular and tubercular 

 articulations. In slab no. 63 (Brist. Mus.). ^ nat. size. 



A slender dorsal rib is preserved in slab 63 (fig. 1), which 

 shows the tubercular and capitular facets to be nearly equal, 

 each about j^ inch wide, and divided by a notch which is 

 somewhat wider. The rib appears to have been directed down- 

 ward, as though it were an early dorsal. The specimen 

 numbered 32 is stouter, has larger articular facets, and a 

 greater depth over the articulation ; only about 3 inches of 

 its length is preserved. These ribs are compressed from 

 front to back and are flattened on the external curved surface. 

 The fossil described as a clavicle has much the aspect of a rib. 



The dorsal vertebra no. 13 Brist. Mus. has the charac- 

 teristic excavation beneath the transverse process, which is 

 margined by anterior and posterior buttresses, which diverge 

 as they descend. The centrum is lyo inch long. Its articular 

 face is flattened, with a margin slightly rounded ; it is 1 inch 

 deep and somewhat narrower. The sides of the centrum are 

 gently concave in length, with a flattened aspect ; the base is 

 rounded from side to side. The zygapophysial processes are 

 well developed. 



No. 14 Brist. Mus. shows the anterior position of the para- 

 pophysial facet for the head of the rib. It also shows that 

 the neural spine is compressed from side to side and elevated, 

 though only preserved for a height of -fa inch. Below the 

 neural arch the centrum shows on the side a longitudinal 

 concave impression. 



No. 10 Brist. Mus. is a dorsal vertebra showing a thick 

 vertical neural spine and strong transverse processes, which 

 appear to be notched out in the anterior margins, as among 

 Crocodiles. 



The caudal vertebra no. 17 Brist. Mus. has the centrum 

 1^\ inch long, y^^y inch high in front, and yV inch high behind. 

 The measurement from the hinder border of the base of the 



