192 



otolith in connection witli the macula acustica recessiis 

 utricnli, and another with the papilla acustica lagense, but 

 none were observed in relation to the three cristse acusticae, 

 althoug-h it is possible that small concretions of chalk 

 were there also. There is a very large sense organ on the 

 inner wall of the sacculus in front, known as the macula 

 acustica sacculi (m. a. s.), and behind, the sacculus is pro- 

 longed upwards and backwards into the digitiform lagena 

 [Jag.), otherwise known as the recessus sacculi or cochlea, 

 the inner wall of which, at about the roof, contains another 

 sense organ, the papilla acustica lagenae {p. a. I.). A 

 constriction or definite sacculo-cochlear canal is not 

 differentiated. 



The sense organ on the floor of the utriculus known 

 as the macula acustica neglecta is entirely wanting in the 

 Plaice. 



The ear and auditory nerve of Pleuronectes flesus have 

 been described by G. Iletzius,t who, with other authors, 

 refers to the utricular, saccular and lagenar otoliths 

 respectively as the lapillus, sagitta, and asteriscus. His 

 description agrees very closely with ours of the Plaice, so 

 that it is only necessary to point out that he did not 

 succeed in finding either a reduced ductus endolymphati- 

 cus or a utriculo-saccular connection. AVitli regard to the 

 latter he says: — "An der unteren Wand des Utriculus, 

 ungefahr gerade unter dem Sinus superior, findet sich eine 

 kleine, trichterformige, hohle Yerlangerung des Utriculus, 

 welche nach hinten geht und sich zu einer feinen Diite 

 verschmalernd an die Wand des Utriculus legt ; ob aber 

 dieser Canal blind endigt, was ich am meisten glaube, 

 oder ob er vielleicht in den Sacculus (als ein Canalis 

 communicans) ausmiindet, kann ich nicht mit Bestimmt- 

 heit angeben." 



t Anat. Unters., 1872, p. 52, Taf. v.., tigs.lU^lS. 



