714 B. W. KUNKEL 



is the orificium inferius canalis semicircularis anterioris. Behind 

 this orifice and below the septum semicirculare anterius are the 

 cavities of the lateral and anterior ampullae which are in the form 

 of lateral pouches from the cavum vestibuli, that of the lateral 

 ampulla being somewhat dorsal and posterior to that of the 

 anterior ampulla. Ventral to the cava ampullaria anterius and 

 lateralis is that of the recessus utriculi which forms a concavity 

 in the lateral wall of the cavum vestibuli, so that at this point 

 the cavum vestibuli exhibits its maximum width from side to 

 side (fig. 6). The cavum vestibuli has a small bulging on its 

 median side about midway between its posterior and anterior 

 ends and at a level with the ventral end of the sinus superior 

 utriculi for the accommodation of the ductus endolymphaticus as 

 it proceeds ventrally from its foramen to its opening into the sac- 

 culus (fig. 4). 



The cavum ampullare posterius, occupying the postero-ventral 

 corner of the cavum vestibuli, is differentiated from the dorsally 

 situated canalis semicircularis lateralis by a medial thickening of 

 the lateral capsular wall on the one hand and a ventro-lateral 

 ridge on the septum semicirculare posterius on the other (fig. 

 2) ; anteriorly the cavity of the posterior ampulla opens into the 

 cavum vestibuli; and dorsally, into the posterior semicircular 

 canal. 



The cavum ampullare laterale lies lateral to the anterior end 

 of the cavum vestibuli and opens medially into it by a wide 

 mouth, anteriorly it opens into the cavum ampullare anterius 

 and ventrally into that of the recessus utriculi; posteriorly it 

 communicates with the canalis semicircularis lateralis through 

 the wide orificium anterius canalis semicircularis lateralis. Its 

 antero-dorsal boundary is formed by the septum semicirculare 

 anterius, its lateral wall is that of the capsule itself; and medially 

 it opens by a very wide aperture into the cavum recessus utriculi 

 and the sinus superior utriculi. At its extreme dorsal end the 

 cavum ampullare laterale is bounded medially by the posterior 

 end of the septum semicirculare anterius. 



The cavum ampullare anterius forms a kind of antero-lateral 

 pocket of the cavum vestibuli, being continuous with the anterior 



