92 THE DESEADO FORMATION OF PATAGONIA 



Of the vertebral column, twenty-six vertebra are pre- 

 served (a few being represented by neural arches only). 

 The atlas and axis are unknown. Five cervicals are pres- 

 ent, each with a short, slightly opisthocoelus centrum, and 

 with low weak spines. The foramena for the vertebra artery 

 are usually large. Cervical 3 has a rather slender trans- 

 verse process, projecting down — and backward. On cer- 

 vicals 4, 5 and 6, these lateral processes are enlarged into 

 broad lamellae, which reach their maximum of size on the 

 sixth. Cervical 7 has no lamella, simply a slender trans- 

 verse process. These transverse processes are strikingly 

 like those of Nesodon. The thoracic vertebrae (of which 

 I have complete or in parts 15) have moderately high spines, 

 which resemble those of Adinotherium, not only in the gen- 

 eral build, but also in the presence of a foramen for the 

 exit of spinal nerves through each neural arch. These 

 foramena can not be referred to as adaptations, but are 

 special features indicating close relationship with the Neso- 

 dontidae. Six lumbar vertebra are present, each having 

 broad depressed centra, and short wide spines. The rest 

 of the column is unknown. 



The distal portion of the humerus is preserved, showing 

 the trochlea to be relatively narrow, with a prominent 

 internal phlange for the ulna. The epicondyles are both 

 small. The supratrochlear fossa is moderately deep, the 

 anconeal fossa very deep, a large perforation connecting 

 the two. Of the ulna, only the distal end is preserved, and 

 it is marked by a prominent styloid process, ending in the 

 facet for the pyramidal, this facet continuing uninter- 

 ruptedly into that for the pisiform. The two ends of the 

 radius are preserved but its length can only be conjectured. 

 The proximal end has a large facet for the humerus; the 

 distal end two facets, for the scaphoid and luna respec- 

 tively, the two being almost continuous, except as the 

 outline of the shallow depressions is constricted near the 

 middle. 



