No. 468.) MUSCLES OF ACANTHIAS AND RAIA. 905 
behind. In all, the fibers are inserted upon the tendon in front, 
and their courses are somewhat oblique near the median side, and 
nearly at right angles to the body axis at their outer margins. 
The lateral portions of the constrictors arise from the ten- 
dons between them and the median muscle, and the fibers run 
laterally to some small cartilages (not always present) and then 
turn dorsally to be inserted on the horizontal tendon. 
Interbranchiales. 
Acanthtas. 
It is a question whether these should be included among the 
superficial circular muscles or not, since they are in no sense 


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branchiales. Csd 3, 
Fic. 7 — Lateral view of Acanthias to show the inter’ 7 3, const " uperioris 
Lin 3; Csv 3, constrictor superioris ventralis 3 ; /ntör, interbranchialis; 7 io) napa 
superficial, nor circular in the same sense that the other muscles 
are, and they lie in a different plane. However, they are closely 
allied with the constrictors in function, assisting in the general 
contraction and expansion of the gill basket, and since compari- 
sons with Vetter are made easier, they are retained here. | 
