ANATOMY AND OLASSIFIOATION OF THE ARENICOLID^l. 605 



All these charactei's point to the otoliths being chitinoid in 

 nature. The absence of gas bubbles under treatment with 

 acids^ precludes the possibility of carbonates having any 

 share in their composition. 



Fauvelj however, though accepting this conclusion for the 

 otoliths of A. Grubii/ states that those of A. ecaudata (a 

 species not examined by Ehlers), when treated with Perenyi's 

 fluid, react quite differently, and that those of the former 

 species stain with htematoxylin, while those of the latter 

 do not. The black granules enclosed in the otoliths of 

 A. ecaudata acquire " I'aspect d'inclusions du quartz. Ce 

 sont probablement des fines bulles gazeuses produites par 

 Paction des acides sur le carbonate de chaux au sein d'une 

 masse solide ou pateuse qui s'oppose a leur fusionnement en 

 une grosse bulle.'^ Further ou he adds, " Les reactions des 

 otolithes avec les colorants indiquent qu'ils sont probablement 

 de nature chitineuse au moins dans leur parti peripherique " 

 (1899, p. 25). 



With the exception of the last sentence our experience is 

 entirely at variance with that of M. Fauvel. We find that 

 the otoliths of A. ecaudata, when treated with acids weak 

 and strong, cold and warm^ with alkalies, and with staining 

 reagents, agree in their reactions in every particular with 

 those of A. Grubii, and we conclude that in both species the 

 otoliths are chitinoid in nature throughout, and do not contain 

 any trace of carbonates, nor do they give off gaseous bubbles 

 on treatment with acid. As mentioned above (p. 504), there 

 are in the centre of some of the fresh otoliths of both 

 species (before treatment with acid) a few small inclusions. 

 Some of these are spherical, and look almost like small gas 

 bubbles having refringent walls, but they are in reality 

 minute spherical granules. Some of the included granules 

 are elongated, rod-like bodies, and others are somewhat 

 irregular in shape. 



' This author (1889, p. 25) mistakes the f^round for Ehlers* conclusion that 

 the otoliths are a secretion of cliitinoici nature, since he says that the Gottingeu 

 zoologist obtained no result with hydrochloric acid. 



