THE EAR OF MAN. 



203 



with the mother surface by means of a single pore. 

 This is true in the case of the anterior and external 

 ear canals of Torpedo (Fig. i, U'). We shall also find 

 that the division of a canal organ may be barren of 

 result so far as the production of a separate canal is 

 concerned, and that in this case the offspring may retain 

 its position in the parent canal. As an instance of this 

 condition in the ear we have the macula neglecta (Fig. 

 7, ma), which has arisen by the division of the parent 

 organ, the primitive sense-organ of the posterior ampulla. 



Fig. 7. — The right internal ear of the European Adder {Tropidonotus 

 natrix), seen from the inside. Figure after Dr. Kuhn. This ear 

 shows very distinctly the division into anterior and posterior chambers, 

 especially in the arrangement of its sense-organs. 



a Anterior ampulla. 



ca Anterior canal. 



ch External canal. 



cp Posterior canal. 



d Ductus endolympLaticus. 



/ Lagena. 



via Macula acustica neglecta of Retzius. 



ins Macula acustica sacculi. 



n Crista acustica ampullarum. 



p Ampulla posterior. 



pb Pars basilaris cochlear auct. 



u Utriculus. 



The early history of the Elasmobranch auditory cap- 

 sule does not differ materially from that of other forms 

 except in the rate of growth. 



In this respect it is a much more favorable object for 



