THE EAR OF MAN. 



199 



posterior divisions, and the parts thus separated are very 

 much the same as in Myxine, showing but sUght modifi- 

 cations of the floor of the sac in the direction of a 



Fig. 4. — The right internal ear of 

 Alligator mississippiensis, seen from 

 the outer face. Figure after G. 

 Retzius. The figure outlines do 

 not bring out the relations of the 

 parts distinctly, and only the more 

 important parts are lettered. 



ac Auditory nerve. 



b Pars basilaris cochleae auct. 



c Anterior canal. 



ch External canal. 



cp Posterior canal. 



/ Lagena. 



n ' Cristae acusticae of the ampullae. 



s Sacculus. 



Fig. 5. — The right internal ear of 

 T Urdus inusica, seen from the 

 inner or neural face. F^igure 

 after G. Retzius. The letters 

 are placed only on those parts 

 of the organ plainly visible in 

 the figure. 



ac Acoustic nerve. 



c Anterior canal. 



ch External canal. 



cp Posterior canal. 



d Ductus endolymphaticus. 



/ Lagena. 



ms Macula sacculi. 



n Lagenar nerve. 



«' Cristae acusticae of the ampullae. 



differentiation of the sense-organs contained, and in the 

 formation of chambers for the reception of the new 

 organs thus budded off. Though sUght, this change 



