716 B. W. KUNKEIi 



the orificium posterius caualis semicircularis latel-alis which is 

 situated immediately ventral to the septum semicirculare poste- 

 rius and somewhat lateral to tlie posterior semicircular canal. 



The canaUs semicircularis anterior curves from its posterior 

 end, first in an antero-lateral direction, then ventrally, and at its 

 extreme antero-ventral portion, somewhat medially, so that its 

 entrance into the cavum ampullare anterius through the orificium 

 inferius canalis semicircularis anterioris is from above and later- 

 ally. It is bounded dorsally, medially, anteriorly, and in part 

 laterally by the corresponding walls of the capsule; ventrally it 

 is bounded by the septum semicirculare anterius which also Ues 

 somewhat lateral to the canal at its posterior end. The antero- 

 lateral end of the canal is Umited behind by a medial tliickening 

 of the lateral capsular wall which separates the cavities of the 

 anterior and lateral ampullae. 



The canalis semicircularis laterahs has two quite distinct 

 portions, a median Umb and a lateral one. The cavity of the 

 median hmb is confluent with that of the utriculus, the pos- 

 terior .ampulla and the inferior end of the posterior canal. It lies 

 lateral and dorsal to the utriculus and posterior ampulla and 

 anterior to the posterior semicircular canal. The cavity of the 

 median limb is bounded laterally by the septmn semicu-culare lat- 

 erale and dorsally by the septum semicirculare posterius. The 

 lateral limb is separated, except at its posterior end, from the 

 median hmb by the septum semicirculare laterale. The canal is 

 horizontal in position and is continuous in front with the lateral 

 ampulla through the large orificium anterius canahs semicu'cu- 

 laris. Posteriorly the lateral limb of the lateral semicircular 

 canal is continuous with the median Umb immediately behind 

 the septum semicirculare laterale and also with the ventral and 

 posterior end of the posterior semicircular canal. 



The cavum saccuh (c.sac, fig. 29) exhibits several features of 

 great morphological interest on account of the relations of the 

 ductus perilymphaticus and the development of the ductus 

 cochlearis in a posterior direction. It has the general form of a 

 flattened pocket which is rather shallow in front and increases 

 quite regularly in depth posteriorly so that the posterior wall is 



