368 HOWARD AYERS 
ventral body wall, especially in the velar region, the fibers of the 
ring muscle interlace across the middle line of the body. 
The velar muscles arise from three territories: first, a strong 
group from the skull behind the eye; second, a band of fibers, 
not continuous, from the lateral part of the neighboring ring 
muscle; and, third, a long but heavy bundle from near the mid- 
WY 
Y= 
= = = _ Yy ———— 
SS Se 
SSS 
Fig. 20 Ventral view of the jaw and velar muscles, derivatives of the trans- 
verse or circular muscles of the head. Ammocoetes. 
ventral line of the branchial skeleton. This latter bundle is 
long, and sweeps forward, upward, and outward into the velar 
body to form the most important muscle of the organ. It is 
the retractor veli. The velum is greatly assisisted in closing 
by the elastic velar cartilage. 
Besides the large jaw muscle already described, which lies 
on the outer face of each jaw bar and spreads out on the ventral 
