44 The Cephalic Veins and Sinuses of Reptiles 
occipitale laterale and the supratemporale. From their origin the fibers 
of the muscle extend mesad in two fan-shaped bundles, one above, the 
other below the vein, which the fibers closely invest in a spiral direction. 
These fibers terminate in the wall of the vein or in the surrounding con- 
——— 
ES —— —S 
SSS 
mK 
Ny 
dts 
\ 
<== = > 
5 = 
SS 
HN) 
Nay A } 
BS > 
WSS 
Fig. 6. M. constrictor vene jugularis interne of Monitor niloticus, left 
side, from above. X 32. 
The general relations were determined by reconstruction. The muscle 
fibers are drawn to scale but their arrangement is somewhat diagrammatic. 
P., part of parotic process; v. 7. 7., vena jugularis interna; v. c. p., vena 
cerebralis posterior. 
nective tissue. Mixed with these there are other spiral fibers which both 
begin and end in the wall of the vein. The middle portion of the muscle 
includes altogether seven or eight layers of these spiral fibers, partly free, 
partly attached. Toward the ends of the muscle the number of layers 
