THE ELASMOBRANCII FISHES 



105 



Superfieial to this ventral region in tlie rays, arising from the fascia of the 

 ventral longitndinal nmscle (the coraeomandihnlaris), is a depressor rostri 

 {d.r., fig. 107). This is inserted far forward between the end of the propter- 

 ygium and the tip of the rostrum {Raja). It has a balancing effect on the 

 levator rostri (see fig. 105, l.r.) previously described. 



Deeper Muscles of Pharynx 



The interbranchials of more specialized Elasmobranchs are usually more 

 completely separated from the constrictors into distinct bundles than are 



c.md 



cbr.. 



Fig. 107. Ventral pharyngeal muscles. (From Tiesing.) A. Torpedo. B. Eaja. 



a.mcl., adductor mandibulae ; cl., tirst gill cleft; c.hr., coracobranchial muscle; c.hy., cora- 

 cohyoideus; c.md., coracomandibularis ; csv., ventral constrictor muscle; d.hm., depressor 

 hyomandibularis ; d.md., depressor mandibulae; d.r., depressor rostri; lls.^, median levator 

 labii; Us.'^, lateral levator labii; Us.*~', fourth and fifth slips of levator labii; n.a., nasal 

 aperture. 



those of HeptancJiKS. In Acanihias (fig. 108a), as is true in general, they lie 

 between the demibranchs, in front of and against the branchial rays of all the 

 whole gills. The dorsal fibers arise from the seams, separating the dorsal con- 

 strictors above the cleft, and from the dorsal extrabranchial cartilages. The 

 shorter, inner fibers are attached to the outer margin of the epibranchial seg- 

 ment of the branchial arch, while the outer fibers pass over to ventral inter- 

 branchial fibers (sharks) . The ventral fibers of the interbranchials arise from 

 the fascia around the coracomandibularis muscle and from the ventral extra- 



