48 THE FROG 
the sartorius; distally it passes beneath the sartorius. About its 
middle it receives a small slip which originates on the tendon of 
one of the heads of the semitendinosus; this will be examined 
later. 
The adductor longus is a narrow thin muscle lying along the 
abductor side of the sartorius, and more or less hidden by it. 
Divide the sartorius about its middle and reflect its parts; this 
will expose the adductor longus, whose fibers mingle with those 
of the adductor magnus along its distal third. 
The gracilis major or rectus internus major, a powerful muscle 
on the adductor side of the adductor magnus. About its middle 
it is crossed by an oblique tendinous inscription or tendinous 
intersection. (The tendinous inscriptions of the limb muscles 
are homologous with those of the abdomen, which are segmen- 
tally arranged—an inheritance from the metameric condition of 
the body muscles in the fishes and the tailed amphibians. ) 
The gracilis minor or rectus internus minor is a narrow flat 
muscle running along the adductor surface of the thigh and 
partly covering the gracilis major. It is sometimes removed with 
the skin. 
(b) Superficial muscles of the postaxial side. This side is 
dorsal when the thigh is adducted and the leg extended. 
The triceps femoris, a very large muscle occupying the entire 
abductor surface of the thigh. It originates by three heads, 
anterior, middle and posterior; the anterior head lies partly on 
the preaxial surface. 
The semimembranosus, a large muscle lying along the adductor 
surface. There is an oblique tendinous inscription running along 
this muscle, as in the gracilis major. 
The ileo-fibularis, a slender muscle lying between the triceps 
femoris and the semimembranosus. 
The iliacus externus arises far up on the crest of the ilium 
and lies between the anterior and middle heads of the triceps 
femoris. 
The pyriformis is a slender muscle passing between the origins 
of the semimembranosus and the posterior head of the triceps. 
(c) The deep muscles of the thigh will be omitted with the 
exception of the semitendinosus, a long slender muscle lying be- 
