544 H. GOVIER SEELEY OST MAUISAURUS GARDNERI, 



separated by a vertical slit. The processes are imperfect ; as pre- 

 served each is 11 inch long and fully -J inch wide. These oblong 

 facets look downward and slightly ontward. The neurapophyses 

 are greatly compressed from side to side. The neural spine is more 

 compressed in front than behind, the base of its posterior margin is 

 parallel to the posterior face of the centrum ; it hangs backward, 

 and measures in the upper part J inch in width. The external 

 width of the neural arch in its middle is 1 J inch. 



Fourteenth to seventeenth — as the articular tubercle for the rib 

 begins to ascend the side of the centrum the tubercle becomes a little 

 prolonged and is rounded. The eighteenth vertebra (PI. XXIII. fig. 

 3) has the base of the neural arch preserved ; its compressed anterior 

 margin is nearly flush with the anterior face of the centrum, but as it 

 ascends it extends forward. The face of the centrum is 64 inches 

 wide. The articular facets for the ribs are nearfy on the middle of 

 the sides of the centrum ; and the base accordingly becomes more 

 rounded from side to side, and is nearly flat from front to back. 

 The tubercle for the rib now steadily ascends the side of the centrum, 

 leaving the base perfectly rounded. The nineteenth has the centrum 

 4 inches long at the base and 3^ inches long superiorly (PL XXIII. 

 fig. 4). The articular surface is more than usually flattened, 6 inches 

 broad, and 4| inches deep. The transverse process was deep and 

 narrow, placed posteriorly, and formed mainly by a downward and 

 backward prolongation of the neural arch. This shows that the true 

 neck is ended, the vertebra belonging to the two or three which form 

 a transition between the cervical and dorsal series, which are con- 

 veniently named pectoral. The twentieth and twenty-first show 

 similar characters ; only the transverse process increases in size and 

 depth, and rises higher. 



Several of the dorsal vertebrae are so similar that one maybe taken 

 as a type (PI. XXIII. fig. 5). It is well preserved, except that the 

 neural spine is broken away. The centrum measures 4| inches in 

 length along the visceral surface from back to front ; but in the line 

 of the neural canal it only measures a little over 3 inches. Under the 

 neural canal the articular face is 5^ inches deep, and as preserved is 5^ 

 inches wide in the middle. The vascular perforations on the base of 

 the centrum are If inch apart; the bone between them is remarkably 

 convex. Below the neural arch the sides of the centrum converge 

 greatly, measuring less than 3 inches transversely. The arch shows 

 the vertically ovate neural canal ; the base of the neural spine is 

 narrow, compressed, and directed backward ; and the broken trans- 

 verse processes are directed outward and upward. The height 

 from the base of the centrum to the shoulder of the transverse process 

 is 7g inches. The transverse processes are compressed from front to 

 back, about 2 inches deep at their origin, and 1 inch wide ; they are 

 twisted so that the superior margin is inclined forward and the 

 inferior margin inclined backward. The whole neural arch is a 

 good deal compressed from back to front. The later dorsal vertebrae 

 are slightly shorter, and the articular face of the centrum becomes 



