XIII.] THE FROG. 223 



p. The tibialis posticus : a slender muscle covered 

 in great part by the gastrocnemius ; it arises 

 from the greater part of the posterior surface 

 of the OS cruris and, passing along the inner 

 side of the ankle-joint, is inserted into the 

 astragalus. 



h. On the opposite side of the hone lie four 

 muscles : viz. — 



a. The peroneus : the largest and most external ; 

 it arises from the outer side of the distal 

 articular end of the femur and, running past 

 the outer side of the ankle-joint, is inserted 

 into the calcaneum. 



/3. The tibialis anticus : a small muscle inside and 

 beneath the peroneus ; it arises from the front 

 of the lower end of the femur and from the 

 capsule of the knee-joint ; below it divides into 

 two parts, one inserted into the dorsal side of 

 the astragalus, the other into the calcaneum. 



7. The extensor cruris hrevis : this lies internal to 

 the upper part of the last muscle; it arises 

 from the front of the distal articular end of 

 the femur and is inserted into the middle 

 third of the os cruris. 



S. The flexor tarsi anterior: this arises where 

 the last muscle ends, and is inserted into the 

 dorsal side of the astragalus. 



6. The nerves of the hind-limb. 



These are now to be dissected out in that leg which 

 has not been used for the muscles. 



