226 ELEMENTARY BIOLOGY. [CHAP. 



/3. The second : same as a, but longer. 



y. The third : a metatarsal bone with three pha- 

 langes. 



8. The fourth : a metatarsal bone and four 

 phalanges. 



. The fifth : like the third, but a little shorter. 



. On the anterior or tibial edge of the foot there 

 are two, small, more or less cartilaginous, 

 ossicles, articulated with the tarsus (c. (3) in 

 such a manner as to resemble an extra digit. 

 This calcar, or spur, supports the horny pro- 

 minence referred to above. 



E. DISSECTION OF THE FROG'S HIND-LIMB TO ILLUSTRATE 



ITS MYOLOGY. 



(For the following dissection it is desirable to have a 

 frog which has been lying some time in spirit.) 



1. Lay the animal on its back, and make an incision 

 through the skin on the front of the limb from the 

 symphysis pubis to the ankle ; then reflect the skin 

 to each side so as to lay bare the parts beneath it; 

 in turning it back note the loose bands and fibres 

 (subcutaneous areolar tissue] with large lymph-spaces 

 between them, which unite the skin to subjacent 

 parts, and which have to be cut through. 



A number of muscles will now be exposed on the 

 front of the thigh and leg. 



2. The superficial muscles on the front of the thigh. 



Separate these gently from one another, tearing 

 through the connective tissue which unites them. 



