132 THE AUDITORY NERVE AND COCHLEA, BY W. WALDEYER, 



cochlea appear in the form of a cone projecting beyond the 

 plane of the sacculus, especially well marked in the Crocodile, 

 which most nearly approximates Birds. In the latter, as 

 Hasse (68) has shown to be probable, the sacculus and utri- 

 culus are fused into an alveus communis (fig. 319 II., US. 



Fig. 319. 



Fig. 319. Three diagrams to show the relations of the auditory 

 labyrinth in the Vertebrate series. 



I. Type of the labyrinth in the Fish. U, Utriculus with the semi- 

 circular canals ; S, sacculus ; C, cysticula ; E, aquseductus vestibuli. 



II. Type of the labyrinth in the Bird. US, alveus communis ; C, 

 cochlea ; UC, commencement of the cochlea ; L, lagena ; Or, canalis 

 reuniens ; E, aquseductus vestibuli. 



III. Type of the labyrinth in the Mammal. U, S, Or, as before ; E, 

 aquseductus vestibuli, dividing into two crura for the utriculus and 

 the sacculus ; C, ductus cochlearis, with F, the caecal pouch of the 

 vestibule, and K, the csecal sac of the cupola. 



The cochlear passage (C) is considerably elongated, and several 

 divisions or segments may be distinguished in it, as the 

 commencement or cochlea proper (U(T) and the flask-shaped 

 terminal segment or lagena (L) of Windischmann. Here is seen 

 also the first indication of a spiral course in the cochlear canal. 

 The communication of the latter with the alveus is effected 

 by a narrow passage, the canalis reuniens of Hensen, which, 

 cording to the observations of Hasse, appears frequently to 



