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Vniversity of California Publications in Zoology [Vol. 18 



is posterior and medial. It is inserted along the inner side ol' the beta 

 cartilage {/3). 



Flexor intcrnus (/. i.). The tlexor internus takes origin along 

 the inner edge of the basipterygiuni, just under the externus and the 

 inner side of the beta cartilage, and under the insertion of the 

 externus. Its direction is posterior and medial and it is inserted on 

 the inner side of the proximal end of the basal piece (&a.). 



pi. pi 



Fig. 8 rig. 9 



Fig. 8. Skeleton of male pelvic fin, Hepianchus maculatus, dorsal vie^v 

 (XI). )3., the beta cartilage; h.^'-, connecting segments; ha., basal piece; ha. p., 

 basipterygiuni; pL, pelvic girdle; ra., radial cartilages. 



Fig. 9. Musculature of male pelvic fin, Heptanchus maculatus, dorsal view 

 (X •%). ad., adductor muscle; cp.. compressor; dl., dilator; f. e., flexor externus; 

 /'./., flexor internus; pi., pelvic girdle; ra., radial muscles; s. 7n., muscle of sac. 



Dilator (dl.). The dilator has its origin on the proximal end of 

 the basal cartilage (ha.) under the beta cartilage. It is inserted in 

 the heavy connective tissue covering the basal cartilage distally, form- 

 ing the inner lip of the groove. 



Sac. muscle {s. yn.). The sac muscle arises on the connecting seg- 

 ments (6^ and h'-) and on the outer side of the proximal end of the 

 basal cartilage. The dorsal fibers are inserted along the inner side of 



