OSTEOLOGY OF THE ABMOHED DINOSAUKIA. 133 



Plate 11. 



Cervical vertebrae and nuchal plates of Slegosaurus stenops Marsh. Type. Cat. No. 4934, U.S.N.M. 

 About 4- nat. size, at, atlas; c 6 , sixth cervical; p. 1 to p. 5, dermal plates one to five, inclusive. Shows 

 the relations of these bones as found in the matrix. From a photograph. See p. 92. 



Plate 12. 



Pig. 1. Posterior dorsal plate of Stegosaurus stenops Marsh. Cat. No. 4714, U.S.N.M. Jnat.size. Viewed 

 from the side. This plate can probably be correlated with No. 13 of No. 4934. This is plate 

 No. 95, diagram 5, quarry 13. See also plate 37. a, anterior border; 6, posterior border. 



See p. 93. 

 2. Ventral view of the same. 

 Drawn under the direction of Prof. O. C. Marsh. 



Plate 13. 



Fig. 1. Anterior caudal plate of Stegosaurus stenops Marsh. Cat. No. 4714, U.S.N.M. J nat. size. Viewed 

 from the side. This is the largest plate of the series and is corre Hated with No. 14 of No. 4934. 

 This is plate No. 10, diagram 5, quarry No. 13. See plate 37, also same as fig. 4, plate 24. 

 a, anterior border; 6, posterior border. See p. 93. 



2. Ventral view of the same. 



Drawn under the direction of Prof. O. C. Marsh. 



Plate 14. 



Series of dermal plates of Stegosaurus stenops Marsh. Type. Cat. No. 4934, U.S.N.M. Plates 

 1 to 14 in sequence. The even numbers represent plates pertaining to the row of the right side; the 

 odd to those of the left. About £ natural size. 



Drawn by Mr. George E. Roberts, under the direction of Dr. F. A. Lucas with additons. Published 

 by permission of the United States Geological Survey. See p. 93. 



Plate 15. 



Caudal vertebrae and spines of Stegosaurus stenops Marsh. Cat. No. 4714, U.S.N.M. J nat. size. 

 Seen from the right side, a, right anterior spine; b, left anterior spine; c, left posterior spine; d, right 

 spine of posterior pair; d' ', basal half of same spine, removed in order to show underlying caudals; e, 

 chevron; /, terminal vertebra; g, twelfth caudal from distal end. Drawn under direction of Prof. O. C. 

 Marsh. See p. 95. 



Plate 16. 



Caudal vertebrae, spines and plates of Stegosaurus stenops Marsh. Cat. No. 4288, U.S.N.M. Seen 

 from the left side. J nat. size. After Marsh, a, right spine of anterior pair; 6, left spine of anterior 

 pair; c, small caudal plate; d, chevron bones; e, right spine of posterior pair; /, left spine of posterior 

 pair: g, terminal vertebra; h, twenty-third caudal vertebra from distal end. 



The bones represented here are essentially in the position in which they were found. Identified 

 and figured by Prof. O. C. Marsh as Diracodon laticeps Marsh. Drawn under the direction of Prof. 

 O. C. Marsh. See p. 95. 



Plate -17. 



Dermal tail spine of Stegosaurus stenops Marsh. Cat. No. 6135, U.S.N.M. J nat. size. (1) and 

 (2) side views; (3) posterior view. It undoubtedly belongs to the anterior pair. From quarry No. 13, 

 diagram 5; No. 31£. See map, plate 37. Drawn under the direction of Prof. O. C. Marsh. See p. 95. 



Plate 18. 



Dermal tail spine of Stegosaurus sulcatus Marsh. Cat. No. 4937, U.S.N.M. Type. J nat. size. 

 (1) external view; (2) internal view; (3) anterior view; (4) section taken at first fracture above the 

 base in figure 2; (5) section taken at second fracture above the base, shown in figure 2. a, anterior 

 sulci; 6, ridge dividing the basal surface; p, posterior sulci; r, ridge between sulci; s, roughened 

 surface for cartilaginous union with spine of opposite side. Drawn under the direction of O. C. Marsh. 



See p. 109. 

 51873°— Bull. 89—14 10 



