158 TWO-TOED SLOTH. 



cient for the foundation of any theoretical expla- 

 nation of the slow movement of the muscles. 

 The British Museum afforded an opportunity of 

 investigating this particular in other slow-moving 

 Quadrupeds, and Mr. Carlisle,, at my request, 

 examined the arteries of the Bradypus tridactylus, 

 of all Quadrupeds yet known the slowest in its 

 movements; when the same remarkable distribu- 

 tion of vessels presented itself, both in the upper 

 and lower limbs ; and the small divisions of the 

 artery, forming the surrounding cylinder, were 

 still more numerous than in the Slow Lemur, viz. 

 not less than 60 or 65, and in the lower limbs, at 

 least, as many: these small cylinders were also 

 connected by several lateral or anastomosing 

 branches. We then opened a specimen of the 

 Bradypus didactylus, an animal far less slow in 

 its motions than the tridactylus. In this species a 

 distribution indistinctly approaching to that above 

 described was discovered, but with much fewer di- 

 visions, and more approaching to the usual distribu- 

 tion in other Quadrupeds. Lastly, A Lemur Loris, 

 or Slender-limbed Lemur, was examined; when it 

 appeared that the trunk of the artery, both in the 

 upper and lower limbs, was surrounded by only 

 four or five smaller cylinders, instead of the nu- 

 merous ones so remarkable in the Slow Lemur, &c. 



