THE VERTEBRAL COLUMN. 



55 



There are facets on the inferior surface of the centrum for the articulation of the chevrons, each 

 of which articulated with two centra. 



A 



Fig. 56. — Spinal cord of sacrum of Triceratops prorsus, No. 4842, 0. S. National Museum. A, Lateral view; B, superior view, a, Anterior; 



p, posterior. 



The distal caudals are longer than broad, have nearly circular extremities, and are slightly 

 biconcave. The neural arches are proportionally higher and there are no transverse processes, 

 as shown in fig. 58. 



Fig. 57.— First caudal of Triceratops prorsus, No. 4842, U. S. National Museum, mounted skeleton. A, Side view; B, anterior view; C, posterior 

 view, a, Anterior; p, posterior; s, neural spine; z, anterior zygapophyses; z', posterior zygapophyses; r, rib borne on the transverse 

 process. One-eighth natural size. After Marsh. 



OSSIFIED DORSAL TENDONS. 



In the tj'pe of Triceratops brevicornus, No. 1834, Yale Museum, there are preserved a num- 

 ber of flattened and elongate rod-like ossified tendons, commencing with the third dorsal and 

 continuing on either side of the neural spines as far back as the posterior dorsals. It is prob- 



Fig. 58.— Median caudal of Triceratops prorsus, No. 2580, U. S. 

 National Museum, seventh caudal of mounted skeleton. A, 

 Lateral; B, anterior; C, posterior views, n, Neural canal; c, 

 facet for chevron; other letters as in fig. 57. One-eighth 

 natural size. After Marsh. 



Fig. 59.— Distal caudals of Triceratops. A, B, C, Lateral, 

 anterior, and inferior views; D, E, F, same views of a 

 more posterior caudal. One-eighth natural size. After 

 Marsh. 



able that these ossifications were present also in the sacral and anterior caudal region, although 

 from the. imperfect condition of the material at hand it is impossible to determine this point 

 with certainty. These ossifications are shown in fig. 48. In cleaning the type of T. calicomis 

 Mr. C. W. Gilmore has found these ossifications along the sacrum. 



