118 The Alligator and Its Allies 
So far as yet known this muscle is not present in 
other reptiles. 
MUSCLES OF THE POSTERIOR APPENDAGES 
Ambiens (Plate III., Figs. 1 and 2, amb, Plate 
IV.; Figs. 2 and 4, amb, Plate V., Figs. 2 and 3, amb) 
(Part I., Rectus femoris and Sartorius partim, 
Vastus internus, Innere Streckmuskelmasse) (Part 
II., Gracilis, Rectus femoris, Sartorius). Arises by 
a short tendon from the anterior spine of the ilium, 
near its union with the pubis. The muscle swells 
quickly to a thick belly which, lying under the skin 
on the forward and inner side of the upper thigh, is 
again reduced to a small, flat tendon which extends 
abruptly over the anteromedial surface of the knee 
joint to its outer side; it then passes through the 
complex of tendons of the femoro-tibialis muscle, 
beneath which it unites with the tendon of origin 
for the peroneus posterior muscle. 
To this muscle is the following strange muscle to 
be ascribed (Part II): it springs, small in extent, 
from the inner surface of the os pubis near the 
acetabulum, extends thence forward around the 
pubis, and runs into a long, thin tendon which 
unites with the insertion tendon of the subcutaneous 
extensor ilio-tibialis muscle. 
Extensor Ilio-tibialis (Plate III., Fig. 2, ex. il. tb.) 
(Part I., Rectus femoris, Adductor flexor, Glutzeus 
maximus; M. du facia lata, Vastus externus, 
