﻿74 ELEMENTARY BIOLOGY. [CHAP. 



a. The distal tarsal series ; two in number in the 

 adult and imperfectly ossified; viz. a larger 

 compressed post-axial element, giving articu- 

 lation to the second and third digits ; a smaller 

 nodular pre-axial piece, giving articulation to 

 the hallux and calcar. 



/?. The calcar (pre-hallux] ; seen to be composed, 

 except in very old frogs, of three pieces, identical, 

 in their characters and relationships, with the 

 component parts of a digit. 



H. Myology; as illustrated in the hind limb. 



(For the following dissection it is desirable to have 

 a frog which has been lying some time in spirit.) 



Pin the animal down on its back, and remove the 

 skin from the hind limbs. 



i . General. 



In dissecting the muscles, separate them gently 

 from one another, tearing through the connective 

 tissue which unites them. 



a. Each is chiefly made up of a main mass, or belly , 

 which is nearly white and readily tears into bundles 

 in a muscle which has been in spirit ; but it is 

 softer, redder, and does not so easily split up in a 

 fresh muscle. 



b. At both ends, in most cases, the belly is replaced 

 by dense shiny tissue forming a tendon. 



c. The tendons are fixed directly or indirectly to 

 some of the neighbouring bones, the less move- 

 able attachment is termed the origin of a given 

 muscle; the more moveable its insertion. 



