THE ELASMOBRANCH FISHES 



259 



ends enlarged into ampullae (a.a. and a.h. respectively) which are placed close 

 together. These two canals join the utriculus (u.) above. The ampulla of the 

 posterior canal (a.p.) is located ventrally and that part of the canal lying 

 near the sacculus is by some considered to be a second or posterior utriculus. 



Fig. 226. Ear of Heptanchus macuJaius. (Duncan Dunning, del.) A. Left ear, lateral view. 

 B. Left ear, median view. 



a.a., ampulla of anterior oblique semicircular canal; a.h., ampulla of horizontal canal; 

 aos., anterior oblique semicircular canal; a.j)., ampulla of posterior canal; en., connection 

 between utriculus and sacculus; d.c., connection between sacculus and posterior oblique 

 semicircular canal; e.d., endolymphatic duct; hr., horizontal canal; ?., lagena; pos., pos- 

 terior oblique semicircular canal; s., sacculus; u., utriculus. 



At its base the utriculus is connected with the sacculus (s.) by a recessus 

 utriculi (at en.). The sacculus is pear-shaped and continues upward in the 

 chimney-like endolymphatic duct, the outer opening of which we saw in a 

 study of the skull {ed., p. 42, fig. 45). From the posterior part of the floor 

 of the sacculus a tongue-like sac, the lagena (?.), projects backward and 

 downward. 



