92 THE MEMBRANOUS LABYRINTH, BY PROF. RUDINGER. 



exists in the mode of attachment to the bone of the two 

 vestibular sacculi. 



In the osseous semicircular canals of Birds, according to 

 Hasse's and my own observations, the position of the utriculus 

 and of the' membranous semicircular canals is also excentric. 

 The membranous ampullae, on the other hand, certainly 

 appear to be the outlets of the osseous canals, being in con- 

 tact with the periosteum of the bone throughout their whole 

 extent. The membranous canals are applied to the periosteum 

 of the convex side of the osseous canals, though they do not 



Fig. 301. 



Fig. 301. Transverse section of an osseous and membranous semi- 

 circular canal from the Goose. ], Superior osseous semicircular 

 canal ; 2, connecting fibres stretching from the periosteum to the 

 membranous semicircular canal ; 3, membranous semicircular canal 

 with epithelial lining ; 4, attachment of the thinner part of the mem- 

 branous semicircular canal to the periosteum. 



appear to be imbedded in the periosteum in the manner I have 

 described above as occurring in Man. Their free wall is 

 connected with the rest of the periosteum by means of a fine 

 plexus, and in the Rat, as well as especially in Birds, Fishes, 

 and the Anourous Batrachia, it may be demonstrated that the 

 space which bounds the free surface of the membranous semi- 

 circular canals and the utriculus is not enclosed by any serous 

 layer lined by epithelium. 



In Fishes also the membranous canals are adherent to the 



