142 AYERS. [Vol. VI. 



nicht behaiipte7i will, dass es Schallejnpfindimgeii zu vermittebi 

 habe, dessen Ftinktion aber in den BereicJi des zur Zeit noch 

 tinvollkommen et'kannten GeJwrsimis fallen wird." I think we 

 may fairly conclude that Mayser was much nearer the full truth 

 than he ever realized when he arrived at the conclusion above 

 quoted. 



era. 



ma 



Cut /J. — The nerve supply of the ear of Profoptertis attitecfens after Retzius. 

 cr.a., nerve of the anterior ampullar sense organ. cr.p., nerve of the posterior 

 ampullar sense organ, cr.e., nerve of the external ampullar sense organ. r.L, ramulus 

 lagenje. vi.s., nerve to the macula sacculi. m.ti., nerve supply of the macula utriculi. 



Relying on the nerve supply, we find in Protopterus a con- 

 dition of the macula neglecta with reference to its nerve supply 

 which indicates that the whole of the sense organ originally 

 budded off from the parent posterior canal organ has not left 

 the parental home, so that the well-defined nerve ramulus neg- 

 lectus is split about the middle of its course, one half passing 

 to the separate vi. ab. and the other apparently to the or. post., 

 and there can be no doubt that the branchlet supplies a portion 

 of the macula abortiva which has remained near the parent organ 

 group to form a part of it. In many fishes the macula abortiva 

 is divided into two very distinct sense organs, which receive 

 each its own nerve supply ; the macula abortiva is thus seen to 

 be not merely a single sense organ, but a pair, the product of 

 a bipartition. The primary macula neglecta does not always 



