THE SENSE-ORGANS AND PEEOEPTION OF EISHES. 235 



villi on the lower (left) side of tlie head do not bear sense-organs, 

 though, as Mr. Cunningham informs me, such organs are found 

 between the villi. 



Conger {Conger vulgaris) . On the outer and inner lips and palate. 



Eel {AnguiUa vulgaris). On the tongue and lips and on the skin 

 of the tubular anterior nostril. 



Dog-fish {Scyllmm canicula). On the tongue and palate and in 

 groups on the papillae of the gill-bars. 



Torpedo {Torpedo marmorata) . No opportunity of dissecting this 

 torpedo occurred, but these organs should be looked for on the 

 papilla bounding the spiracle of this species, in which place their 

 occurrence would be interesting. 



It is of course not suggested that these organs do not occur also 

 on other parts of the animals named, as such structures are very 

 generally distributed among fishes. 



The nature of these structures is sufiiciently shown by the figures. 

 Upon the lips of the conger two types are found, of which the 

 most usual is shown in fig. 13. The sense-organ is here seen to 

 lie on the general surface of the skin, which is very thick. Below 

 the sense-organ a narrow channel passes up through the whole 

 thickness of the skin, and in this the nerve travels up to the sense- 

 organ. The other type of sense-organ found in the same situation 

 is precisely similar, except that it does not lie superficially but at 

 the bottom of an open pit, depressed below the surface of the skin. 



The nerve-supply of the sense-organs of the pharynx of the mullet 

 {Mugil), &c., and of the barbels of the recklings {MotelJa), &c., 

 differs from these in that the skin is not channelled for the passage 

 of the nerves to them. On the contrary, the fibres, after leaving 

 the nerve-trunks, jjass bodily through the hasement-memhrane and 

 amongst the cells of the skin to break up on the sense-organs {v. 

 fig. 11). 



Senses of Fishes which seek theie Food by Scent. 



Smell. — The majority of fishes seek their food chiefly if not en- 

 tirely by sight, but a certain number hunt for and recognise it by 

 the sense of smell alone, while a few species are also aided in seek- 

 ing by special organs of touch. The following is a complete list of the 

 fishes which have been observed by me to show consciousness of food 

 which was unseen by them ; and, as will be hereafter shown, there is 

 evidence that they habitually seek it without the help of their eyes. 



Protopterus annectens. Nursehound {Scyllium catulus). 



Rough dog-fish {Scyllium cani- Skate {Baia hatis). 



cula). Conger {Conger vulgaris). 



