76 Description of the Bones of a new Fossil Animal. 



9^ inches; from the coronoid process to the base of the cubit, 

 6 T 7 g inches; smallest transverse diameter of the cubitus, 3^ in- 

 ches, and reduced in parts by muscular pressure from one and a 

 half inches to half an inch in thickness. The carpal articula- 

 ting surface is broken. 



Radius. — There exists in this collection two specimens of this 

 bone of different sizes, both with the distal extremity broken off 

 and lost ; the smaller of the two, which apparently was attached 

 to the above described cubitus, is about 7 inches long and 2J 

 inches thick, compressed in its antero-posterior direction, and 

 strongly marked by grooves for muscular attachments; its proxi- 

 mal extremity is terminated by a glenoid cavity, which moves 

 on the external condyle of the humerus, measuring 1£ inches by 

 2J inches, and is in continuance with a protuberance on the in- 

 ner border, with a convex surface, articulating with the disk on 

 the outer and superior portion of the ulna. The larger radius 

 is nearly three inches thick, and eight inches long from the frac- 

 tured end. The inferior articulating surface being lost in both 

 specimens, we can offer no views of its form. 



Carpus. — Five bones of the wrist have been preserved ; two 

 only of the upper row have been brought to articulate with each 

 other. In general character, these carpal bones resemble those 

 of the megatherium, in which, as in the present species, both 

 bones of the fore-arm are articulated with the bones of the carpus. 



Claws. — Four of the ultimate or ungueal phalanges, forming 

 a continuous series, have been preserved ; these are too small to 

 have belonged to the large individual, their size being better 

 adapted to the smaller one. These are much smaller than those 

 of the megalonyx, and in general form approach nearest to the 

 ungueal phalanges of the orycteropus. The upper border of the 

 largest is convex, but less so than a similar bone in the mega- 

 lonyx or megatherium, and rather more curved than that of the 

 orycteropus ; but the two next in size, like those of the last nam- 

 ed animal, have the upper borders nearly straight, but in the 

 fourth one, on the contrary, this border is in both rather concave. 

 They all possess the bony tubercle, together with the foramina 

 on its posterior inferior surface, like those of the megatherium 

 and megalonyx ; but they differ from these last named animals, 

 in the absence of the bony sheath surrounding the base of the 

 claws. The articulating surface in each is divided into two fa- 



