126 The Alligator and Its Allies 
Achilles, which portion may be followed to the 
rudiment of the fifth toe. On the outer side of 
this toe rudiment is attached a tendon from the 
tibial border of the muscle. 
In the crocodile. This muscle is here divided 
into two parts, of which the one that springs from 
the anterior surface of the fibula is inserted on the 
toe rudiment, while the greater and outward part 
extends over the calcaneum bone and has the same 
distribution as in the alligator. 
Peroneus Posterior (Plate IV., Figs. 3 and 4, peron. 
post., Plate V., Figs. 2 and 3, peron. post.) (Plan- 
taris). Springs chiefly from the tendon of the 
ambiens muscle running over the knee and forms 
the direct continuation of this muscle. Besides 
this come tendinous fibers from the insertion 
tendons of the femoro-tibialis and extensor ilio- 
tibialis muscles; and finally supporting fibers from 
the outer, end-tendon of the ilio-fibularis muscle. 
The fibers of this muscle pass partly into the 
fibular portion of the caput femoralis of the gas- 
trocnemius, while the chief mass of the muscle is 
inserted on the posterior surface of the calcaneum. 
Gastrocnemius (Plate III., Figs. 1 and 3, cap. 
int. gastr., Plate IV., Fig. 4, cap. int. gastr. and 
cap. ext. gastr., Plate V., Figs. 2 and 3, cap. ext, 
gastr. and cap. int. gastr.) (Solenmuskel, Outer 
head of gastrocnemius). This is the strongest 
superficial flexor muscle on the posterior surface 
of the lower leg; it consists of two heads: I. 
