THE EAR. 



399 



buted the B. saccuH [rs) from above ; a large otolith rests on the 

 macula and occupies a large portion o£ the cavity^ more especially 

 the lower portion. The tubular ductus endolymphaticus {dé) arises 

 by a narrow oval opening placed in the upper and inner part of the 



Fig. 249. 



II. 

 III. 

 IV. 



«p. 



cip. 

 rpb 



The membranous labyrinth of Rana esculenta ; after Retzius. 



Part of membranous labyrinth to show relations of the ductus and saccus endolymphatioua 



to the cochlear part ; magnified. 

 The recessus utriculi and the external ampulla ; magnified. 

 To show tegmentum vasculosum, pars basilaris, pars neglecta, etc. 

 To show relations of the cochlear part to the pars neglecta. 



Ampulla anterior. 



Ampulla externa. 



Apertura lagenae. 



Posterior ampulal. 

 apn Apertura partis neglectae. 

 au. Apertura utriculi. 

 ca. Canalis m. anterior. 

 ce. External semicircular canal. 



Posterior semicircular canal. 



Opening into pars basilaris. 



Crista acustica. 



Canalis utriculo-saccularis. 



Ductus endolymphaticus. 



Ductus perilymphaticus. 



wallj runs upwards and to the angle between the utricle and the 

 si?ms superior, continues in the same direction for a short space, and 

 then curves inwards to pierce the apertura aquaeductus vestibuli, and 

 so reach the cranial cavity. It then forms a large, thin-walled sac 



