EXPLANATION OF THE PLATES. 63 



Fig. 1. Fragment of the scapula. Dorsal view, representing the coraco-acromiaJ arch entire. 



Fig. 2. Inferior view of the same specimen, exhibiting the glenoid fossa and the coraco-acroraial arch. 



Fig. 3. Inner or subscapular view of the lower portion of the scapula of a young animal, exhibiting 

 the development of the coracoid process us a distinct loone. A, B, suture of the coracoid process ; C, 

 partial epiphysis of the glenoid fossa. 



Fig. 4. Inferior view of the same specimen from which the preceding figure was taken. 



Figs. 3 and 4, are from one of the specimens upon which Dr. Harlan originally proposed the Mega- 

 lonyx laqueatus. 



Fig. 5. The clavicle. 



Fig. 6. Palmar view of the right scapho-trapezial bone A, and the lunar bone B. 



Fig. T. Intercarpal view of the same specimens, c, articular surface for the first metacarpal bone ; 

 d, articular surface for the trapezoid bone; e,f,g, three articular surfaces for the os magnum; //, 

 articular surface for the cuneiform bone. 



Fig. 8. A, B. Radial articular surfaces of the same specimens. 



Fig. 9. Palmar view of the right lunar bone A, and the cuneiform bone B. c, articular surface for 

 the scapho-trapezial bone ; d, articular surface for the radius ; e, articular surface for the ulna ; /, arti- 

 cular surface for the pisiform bone. 



Fig. 10. Palmar view of the right os magnum A, and the unciform bone B. c, articular surface for 

 the trapezial portion of the seapho-trapezium ; d, articular surface for the lunar bone; e, articular sur- 

 face for the cuneiform bone. 



Fig. 11. A, B. Radio-ulno-carpal view of the same specimens as those represented in figure 9. c, 

 articular surface for the ulna ; d, articular surface for the pisiform bone. 



Fig. 12. A, B. Intercarpal view of the same specimens as those represented in figure 10. c, d, e, 

 the corresponding articular surfaces to those marked with the same letters in figure 10. 



Fig. 13. A, B. Metacarpal view of the same specimens as those represented in figures 10 and 12. 

 c, d, e, articular facets for the median metacarpal bone; /, articular surface for the annular metacarpal 

 bone ; g, articular surface for the auricular metacarpal bone. 



Fig. 14. The right pisiform bone, a, articular surface for the unciform bone and the ulua. 



PLATE IX. 



Megalonyx jEFFERSoxn. All the figures are one-third the diameter of nature. Figures 1 to 4 

 inclusive are from specimens in Dr. Owen's collection, and the others are from specimens of Jefferson's 

 collection. 



Fig. 1. Anterior view of the left humerus. 



Fig. 2. Posterior view of the left humerus. 



Fig. 3. Head of the same specimen. 



Fig. 4. Antebrachial border of the same specimen. 



Fig. 5. Front view of the left radius and ulna. 



Fig. 6. Carpal extremities of the same specimens. 



Fig. t. Pro.ximal end of the left ulna. 



PLATE X. 



Megalontx Jefferson u. Figure 1 is one-third the diameter of nature, while all the other figures 

 are one half. Figures 1,18, and 19 are from specimens of the Jefi'erson collection, and the others are 

 from specimens in Dr. Owen's collection. 



Fig. 1. Dorsal view of the left radius and ulna. 



Figs. 2-5. Outer view of the median metacarpal bone and phalanges. 



Figs. 6-9. Upper view of the median metacarpal bone in conjunction with the annular metacarpal 

 bone, and of the median jihalanges. 



