Mr. Carlisle on a Peculiarity, &c. gg 



into a number of equal-sized cylinders, which occasionally 

 anastomose with each other. They are exclusively distributed 

 on the muscles ; whilst the arteries sent to all the parts of the 

 body, excepting the limbs, divide in the usual arborescent form; 

 and, even those arteries of the limbs which are employed upon 

 substances not muscular, branch off like the common blood- 

 vessels. I counted twenty-three of these cylinders, parallel to 

 each other, about the middle of the upper arm ; and seventeen 

 in the inguinal fasciculus.* 



This fact appeared at first too solitary for the foundation of 

 any physiological reasoning; but, having since had an oppor- 

 tunity of prosecuting the inquiry, among animals of similar 

 habits and character, I have been encouraged to hope that the 

 result may eventually assist in the elucidation of muscular 

 motion. The Bradypus tridactylus, or great American Sloth, has 

 a similar distribution of the arteries of its limbs to that already 

 described in the Lemur tardigradus; which will be better under- 

 stood by the annexed figures. See Plate II. figs. 1 and 2 ; and 

 the explanations. The communications of these vessels with 

 each other are' more frequent than in the Lemur tardigradus, 

 and their number is considerably greater. I counted forty-two 

 separate cylinders upon the superficies of the brachial fasci- 

 culus ; and, from the bulk of the fasciculus, I estimate that 

 there were twenty, or more, concealed in the middle. The 

 lower extremity has its arteries less divided, and they are of 

 larger diameter. I observed only thirty-four branches in the 

 middle of the thigh; and the first series of ramifications were 

 larger than the subsequent ones. May not this have some 

 relation to the greater distance of the lower limb from the 



* See Plate I. and its references, page 103, 

 OS 



