Observations on the Anatomy of the Sloth. 503 



soles of its feet to the sides, or even opposite surface of the Umb 

 or trunk of the tree, on which it is climbing ; its long clav/s and 

 powerful muscles harmonizing with this arrangement, enable 

 this animal to remain thus suspended, for hours and days with- 

 out fatigue, and even to sleep, in a position so awkward and 

 painful to other animals. 



The organs of mastication, the peculiar construction of the 

 shoulder, with many other interesting details, have been already 

 fully commented upon by Cuvier, in his " Ossemens fossiles :" in 

 the present instance, the rudimentary clavicles and coraco- 

 acromion pieces were cartilaginous. We have only further to 

 remark, as entering into the composition of the knee joint, the 

 existence of a large sesamoid bone at the exterior portion of the 

 head of the fibula ; and that, in two crania which we possess of 

 this animal, all the canine teeth are worn on their posterior 

 surfaces. 



The size of this species has been variously estimated, at from 

 14 to 28 inches in length ; the skeleton of our specimen is 22 

 inches in a straight line from the tip of the snout to the ex- 

 tremity of the tail. 



The following represent the measurements in detail : — 



Inches. Tenths. 

 Length of the Head, 2 6 



Neck, 4 6 



Body, 9 



Sacrum, 2 4 



Tail, 3 4 



22 00 



Length of the arm 7 inches 2 tenths : length of the fore arm 6 

 inches : length of the hand, including the wrist, 5 inches : great- 

 est circumference of the body 13 inches. 



The crowns of the molars appear peculiarly adapted to the 

 mastication of leaves. The foetus in utero possessed the same 

 number of teeth, similarly arranged, and with the exception of 

 being more conical towards the crown, presented perfect 

 miniatures of those of the adult animal ; and from the state of 

 their developement, no doubt can exist of the capacity of these 

 animals to masticate from the period of their birth. The foetus 

 was clothed with a profusion of hair, marked in every respect 



