718 B. W. KUNKEL 



The canal opens at its anterior end in an oblique plane along the 

 median wall of the cochlea a short distance in front of its extreme 

 posterior end (fig. 3, left side). The ductus perilymphaticus 

 fills the canal completely. 



The septum semicirculare posterius is in the form of a horizon- 

 tal plate which extends laterally from the median to the lateral 

 capsular wall and septum semicirculare laterale. It passes dor- 

 sal to the cavum ampullare posterius and ventral to the canalis 

 semicircularis posterior as has been aheady noted. The sep- 

 tum begins at its posterior end as a ridge which extends laterally 

 from the median capsidar wall and differentiates the canalis 

 semicircularis posterior from its ampulla. It terminates abruptly 

 anteriorily behind the sinus superior utriculi. Dorsal to the 

 septum is situated the canaUs semicircularis posterior while ven- 

 tral to it are the ampulla posterior, the utriculus, and the median 

 limb of the lateral semicircular canal. The two latter are differ- 

 entiated from each other by a broad ridge on the under side of 

 the septum. 



The septum semicirculare laterale is a vertical plate situated in 

 a longitudinal plane separating the ampulla posterior, the cavum 

 vestibuli, and median limb of the lateral semichcular canal on 

 the one hand from the lateral Hmb and ampulla on the outer 

 side. At its posterior end the lateral margin of the septum semi- 

 circulare posterius and the lateral capsular wall unite. 



The septum semcirculare anterius is a plate which extends 

 between the lateral and median capsular walls in an oblique 

 position, its anterior end lying somewhat higher than its posterior. 

 It lies dorsal and medial to the ampullae lateralis and anterior, 

 and ventro-lateral as well as posterior to the canaUs semicircu- 

 laris anterior. The septum is slightly twisted; at its posterior 

 end its lateral margin lies at a higher level than its median mar- 

 gin, while at its anterior end the lateral margin is lower than the 

 median margin. In front the septum arises from the median 

 capsular wall as a ridge which projects laterally and differentiates 

 the anterior semicircular canal from its ampulla. Posteriorly 

 the septum arises from the lateral capsular wall as a ridge which 

 demarcates the cavum sinus superioris utricuh from that of the 

 lateral ampulla. 



