22 ' MEGALONYX. 



ward, and bounded externally by a rounded protuberance. The posterior articular 

 processes have convex facets directed downward and outward. 



The transverse processes are supported by a pair of abutments, with the foramen 

 for the vertebral artery intervening, of which one is derived from the side of the 

 body, the other from the side of the spinal arch. At their outer part they are 

 prolonged anteriorly and to a greater extent posteriorly; and they terminate in 

 notched extremities. 



The height of the fifth vertebra from the inferior margin of the body posteriorly 

 to the end of the spinous process is five and a half inches, and the height of the 

 seventh vertebra in the same position is seven inches. 



Dorsal Vertehrce. — Of these there are two in the collection of Dr. Owen ; one from 

 the anterior portion of the series, the other from the posterior portion. 



The specimen of an anterior dorsal vertebra has lost the posterior epiphysis of 

 its body, and has its spinous process broken away. The body of this bone is trans- 

 versely elliptical, and its anterior surface is a little over two inches in breadth and 

 an inch and a half in depth. 



The sides of the spinal arch are over two inches wide, and gradually spread from 

 each other posteriorly. The anterior angles of their base curl upward into a pro- 

 cess supporting the corresponding articular facet, which is concave and directed 

 upward and inward. The posterior articular facets rest upon the under side of the 

 posterior margin of the spinal arch. They are oval and slightly concave, and are 

 directed downward and inward. 



The spinal canal is trilateral and expands posteriorly. Its entrance anteriorly 

 is a little wider than the body of the bone, but the vertical diameter is a little less. 

 The spinous process, judging from its broken base, appears to have had the same 

 form as in the posterior cervical vertebrae. The transverse processes extend nearly 

 two and a half inches from the body, and at their extremity inferiorly present a 

 deep concave facet for articulation with the tubercle of the rib. At the anterior 

 part of the body on each side, a small articular facet exists for articulation with the 

 head of the rib. 



The breadth of this vertebra from the extremities of the transverse process is 

 seven inches. 



The posterior dorsal vertebra above indicated is in three fragments, and the 

 body has lost its anterior epiphysis. The specimen is twice the bulk of that just 

 described. The body of the bone is demi-cylindroidal and constricted between the 

 epiphysial surfaces. The posterior epiphysis is three and a half inches broad and 

 three inches deep. 



The spinous process is five and a half inches in length from the margin anteriorly 

 of the spinal canal, inclines backward, and terminates in a stout convex tuberosity. 

 The spinal canal is nearly circular, and is about two inches and a half in diameter. 

 The anterior and posterior articular processes are simple elliptical planes, resting 

 upon the corresponding portions of the spinal arch ; the former being directed up- 

 ward and slightly outward and forward, the latter downward and slightly inward 

 and backward. 



The transverse processes are thick, curved tuberosities, projecting from the spinal 



