CEPHALOPODA. 619 



into three caruncles {e, f, g), very soft in texture, and beset with 

 numerous papillae."* 



Siebold and Kollikerf describe the olfactory organs of the Dibran- 

 chiates as situated in the neighbourhood of the eyes, and consisting 

 each of a cavity with tumid borders, or of a cutaneous fossa which 

 has an opening and, sometimes, at the bottom, a whitish papilla. 

 The nerves of this organ arise from the optic ganglion. They are 

 at first closely united with the optic nerves, enter the orbit with 

 them, and extend along its posterior wall to the olfactory papillae, to 

 which they are distributed in a radiated manner.^ The sense of 

 smell has been attributed to the Cephalopods by all naturalists who 

 have observed their habits from Aristotle to Cuvier. It appears that 

 the ancient Greek fishermen were in the habit of attaching strong- 

 scented herbs to their baits to deter the cuttle-fishes from coming to 

 devour them. 



The organ of hearing consists of two vestibular cavities, excavated 

 in the thick and dense under part of the cartilaginous cranium which 

 supports the sub-oesophageal ganglions. § In Sepia and Loligo several 

 obtuse elastic processes project from the inner surface of the cavity, 

 which contains a delicate sacculus and otolite. A slender canal, 

 lined by a ciliated epithelium, forms part of the vestibule in the 

 embryos of Sepia and Loligo.\ The acoustic nerve is spread over 

 the sacculus, and is impressed by the movements of the otolites, 

 which respond to the sonorous vibrations that may be strong enough 

 to affect the body generally. The sinuosities in the intervals of the 

 vestibular processes seem to be the first rudiments of those which in 

 Vertebrata are extended in the form of canals and spiral chambers, 

 within the substance of the dense nidus of the labyrinth. In the 

 Octopus the vestibules are nearly spherical with a smooth internal 

 surface ; the otolite is hemispherical ; in the Eledone it is shaped 

 like the shell of a limpet, with the apex rounded and curved back- 

 ward, and appears not be calcified : in other Cephalopods the otolites 

 contain carbonate of lime. 



The orbit in the cuttle-fish is formed posteriorly by a thick car- 

 tilaginous cup (Jig. 224, a a), and is completed anteriorly by a dense 

 white fibrous dermal membrane (6), which becomes transparent at 

 the anterior part of the globe, and forms the cornea (c). The cornea 

 and the fibrous tunic are lined by a thin serous membrane, which is 

 reflected over the anterior part of the sclerotica {d), passes through its 

 anterior aperture (to which the cornea does not adhere), like the 



* CCCCIV. p. 532., fig. 218. f XXIV. p. 381. t CCCXCI. 



§ CCCLXXIX. p. 380. II CCCXCI p. 105. 



