334: PROCEEDINGS OP THE CANADIAN INSTITUTE. 



5. Adductor Profundus, (No. 16, Cuv.) 



This muscle (Fig. 5, AdP) lies below the ventral musculature. It 

 arises from the posterior portion of the lower surface of the coracoid, 

 extending inwards as far as the middle line. It passes below the 

 thin bridge-like spiculum of bone on clavicle, and is inserted into the 

 groove at the base of the semi-circular process at the base of the first 

 ray. 



Innervation. — Same nerve that supplied abductors. 



Action. — It draws the ray, and with it the entire fin, towards the 

 body. When the fin is abducted it acts obliquely on its point of in- 

 sertion, and accordingly gives the rotation necessary to release the 

 ray from its fixation. 



VIII.— MUSCLES OF THE PELVIS AND PELVIC FIN. 



The muscles which act on the pelvis have already been described in 

 •connection with the trunk musculature. The posterior fibres of the 

 great ventral muscle and the portions of the infracarinales act as pro- 

 tractors and retractors of the pelvis. 



The muscles which arise from the pelvis are those which move the 

 fin. These are arranged in two layers on the ventral and dorsal sur- 

 faces of the pelvis, those of one side being separated from those of 

 the other by a fibrous septum formed by a continuation backwards 

 of the fascia which separates the two halves of the great ventral mus- 

 culature. The ventral muscles act as abductors, the dorsal as ad- 

 ductors. 



1. Abductor Superficial^ Pelvis, (Pig. 7, AdS). 



Arises from the thickened outer edge of the pelvis, and posteriorly 

 from the aponeurosis formed by the median fibres of the ventral 

 muscle (VA) and the septum between the muscles of opposite sides. 

 The outer fibres run almost directly backwards, the inner almost 

 directly outwards, the former being inserted into the base of the outer 

 ray, and the latter into that of the inner one, while the intermediate 

 fibres pass to the intermediate rays dividing imperfectly into separate 

 tendons. 



Action. — Abducts (i.e., pulls downwards) the fin, and also separates 

 the rays. 



