The Muscles II5 
IV. Rectus internus. On the inner surface 
of the rectus ventralis, from which it is separated 
by the intervening aponeurosis of the rectus muscle, 
appears a muscle lying on the outside of the dia- 
phragmatic muscle. It extends as a broad band 
from the breast to the anterior border of the os 
pubis, with longitudinally directed fibers, to half 
the width of the rectus ventralis muscle. 
Intercostales (Zwischenrippenmuskeln). The 
intercostal muscles in the Crocodilia are, in pro- 
portion to the strength of the ribs, of slight struc- 
ture; they extend only from rib to rib and are, 
therefore, very short, though fairly thick. They, as 
usual, consist of the outer muscles with a direction 
like that of the external oblique, and of an inner 
muscle extending in the opposite direction, 7.e., 
at right angles. The internal muscles are espe- 
cially well developed in the breast region and pass 
over into the internal oblique muscle. 
Quadratus Lumborum (Carré des lombes, Vier- 
eckiger Lendenmuskel, Psoas major). A strong, 
thick muscle that springs from the inner surface 
of the transverse processes and bodies of the last 
six presacral and the first sacral vertebre. The 
muscle diminishes as it passes in a caudoventral 
direction and is inserted with a strong tendinous 
band to the trochanter femoris. 
The Diaphragm (Diaphragmaticus, Zwerchfell, 
Bauchfellmuskel). Closely inclosed between the 
skin and muscle of the abdomen, in the Crocodilia, 
