84 



MEDUSA. 



and others of sight. Some species possess both, but, as 

 a general rule, among Medusfe, where organs of hearing 

 are present, those of sight are wanting, and vice versa. 

 It niay seem extraordinary tliat there should be such 

 differences of opinion as to these organs. The earlier 

 naturalists, however, had but imperfect microscopes, 

 and probably often examined specimens in a bad state 

 of preparation. As regards the alternative between 

 the view that they served as eyes and that which 

 regarded them as ears, it must, moreover, be remem- 

 bered that as long as we merely know that there was 

 a capsule containing a transparent body, the function 

 might well be doubtful. 



The auditory organs of the jelly-fishes were first 

 recognized as such by KoUiker.* They are ranged 

 round the umbrella, and vary considerably in number, 

 ranging up to sixty in Cimina, eighty in Mitrocoma, 

 and as many as six hundred in (Equorea. 



There are three types. In the first, the auditory 

 organ is an open pit, lined with cells. The majority of 

 those on the outer side contain an otolithe, while a row 

 on the opposite side are strap- 

 shaped, their free ends termi- 

 nating in auditory hairs, which 

 reach to the cells containing 

 the otolithes, while their inner 

 ends are continuous with fibres 

 from the inner nerve-ring. 



In such an auditory organ 

 as that of Ontorchis (Fig. 51), 

 the otolithes present a very deceptive resemblance to 

 the lenses of an eye. 



• "XJeber die Eandkorper der Quallon," Frork^is Ncue Not, IS13, 



Fig. 51. — Auditory organ of Ontor- 

 chis h'i:ii':iihauri. 



