666 Dr. HARRIS H. WILDER, 



and takes a direction nearly perpendicular to the axis of the body, 

 the others lying diagonally and parallel to each other. 



The last three may be cut away from their origin in the dorsal 

 fascia, and reflexed, thus bringing to view their nerve supply from 

 small twigs mostly of the vagus system. By farther separation of the 

 connective tissue, the 2"'' and 3"' may be traced to their insertion, 

 that of the 4"' being hidden by the procoraco-branchialis. The levator 

 arcus primi is now exposed, showing upon its surface the Ramus 

 lingualis glossopharyngei, which issues from between the fibres of the 

 muscle and passes over the P' gill arch. 



Origin. All four muscles arise from the fascia dorsalis, the 

 three last by a narrow, and the first by a much broader origin ; this 

 last being mostly covered by the other three muscles. 



Insertion. They are inserted each into the middle third of 

 epibranchiale 1, 2, 3 and 4 respectively. 



Innervation. The first levator is supplied by twigs given ofi" 

 from the Ramus lingualis IX while passing through the muscle. 



The second is supplied by that branch of glossopharyngeus which 

 is distributed to the 2°'^ external gill. The third and fourth are sup- 

 plied by small twigs from the vagus. 



11. Procoraco-branchialis (Adductor arcus III, Fischer, 



cleido-branchial, Leon Vaillant) (figs. 2, 1 p.b.). 



Preparation. This muscle reaches diagonally across from the 

 last external gill to the shoulder girdle, and must first be removed 

 before the subsequent muscles can be studied. 



By drawing the entire gill apparatus a little forward, the muscle 

 can be put on the stretch and is thus best prepared. Cut it through 

 in the middle, taking care not to harm a large branch of the vagus, 

 which runs closely adherent to the internal side, and supplies the 

 muscle. Reflect the two portions. 



Origin. From the boundary between scapula and clavicle, from 

 the medial half of the anterior border of the scapula, and from the 

 pars suprascapularis. 



Insertion. Mostly by a tendon, into the dorsal extremity of 

 epibranchiale 4. A few fibres are inserted into the connective tissue 

 of the 3"^ external gill. 



The fibres which , according to Fischer and others , are said to 

 be inserted into the 3"' gill-arch, do not appear to be constant. 



