COLOURS, TASTE, SMELL AND HEARING. 19 



disappcai-ed. While in some mountain streams they are present in fish weighing 

 as niucli as half-a-ponnd. 



Wo may generally anticipate non-migratory forms being more vividly- 

 coloured than such as are periodically residents in the sea, or brackish water, 

 Avhich seems, as a rule, to cause a fish to assume a general silvery* or steel colour 

 with or witliout X-shaped or starredf black spots, and these latter are not 

 surrounded by a light circle. On the other hand, as will be more fully referred 

 to under the head of " trout," some examples from lochs and also from fresh-water 

 localities where access to or from the sea is impossible, are found to be of a silvery 

 colour, due to local circumstances or possibly sterile conditions of the specimens. 



The sense of taste in fishes is popularly considered to be but slightly 

 developed, a conclusion to a great extent arrived at because most fish bolt their 

 food. On the other hand, the angler, line-fisherman, and pisciculturist perceivo 

 that they will often ravenously devour one kind of food, rejecting another, that 

 they have their likes and dislikes, which must have some connection with the 

 character of the object or else with its taste. 



That fishes possess the sense of smell has long been laiown, and in olden 

 times anglers employed certain essential oils to add zest to their baits. Some 

 Salmonoids are now and then captured which, due to accident, disease, here- 

 ditaiy malformation or want of development, ai-e found totally devoid of 

 vision, and yet are in good condition and well-nourished, and the question 

 arises how did they obtain food ? In addition to the sense of touch they are 

 provided with organs of smell to enable them to receive impressions from the 

 surrounding medium, directing them to their food or warning them against 

 impurities in the water. These organs are situated much as we perceive them in 

 the higher animals, but they do not communicate with the mouth, nor are they 

 related to the function of breathing, for were their delicate lining membrane 

 subject to incessant contact with currents of water, it would doubtless have a 

 deteriorating effect, owing to the density of the respired element. The nosti-ils 

 are depressions or cavities, lined with a large amount of a highly vascular pituitary 

 membrane, packed into as small a compass as possible, while there are two external 

 openings situated on either side of the median line of the snout. 



Hearing is developed in fishes, and it is very remarkable how any diversity of 

 opinion can exist as to their possessing this sense. Lacepede relates how some 

 fish, which had been kept in the basin of the Tuileries for upwards of a century, 

 would come when they were called by their names ; while in many parts of 

 Germany, trout, carp, and tench were summoned to their food by the ringing of a 

 bell. The internal auditory apparatus is placed within the cranial cavity ; its chief 

 constituent parts are the labyrinth, which is composed of three semi-circular 

 canals and a vestibule, which latter expands into one or more sacs, where the ear- 

 bones or otoliths are lodged. A tympanum and tympanic cavity are absent. 

 They possess fontanelles between the bones forming the roof of the skull, and 

 which, being closed by very thin bone or skin, sounds from the surrounding 

 water may be readily transmitted to the contiguous internal ear. But the chief 

 mode in which hearing is carried on must be due to the surface of the fish being 

 affected by vibrations of the water, and the sounds are transmitted directly to the 

 internal ear, or else by means of the air-bladder acting as a sounding-board. 



The methods adopted by fish to communicate with one another are various, 

 thus in some forms a distinct sound is emitted, as in the horse-fishes, Hiiipocampi : 

 while among the Salmonidce it is not unusual for the angler, when the water is 



* Mr. Lockington (American Naturalist, May, 1880, p. 368) observed somewhat the same 

 phenomenon in the Western hemisphere, where the Salmo irideiis, a resident in all Calif ornian 

 brooks and rivers, descends in the autumn to the sea, and when in salt water changes its colour 

 to a steel blue, while its spots mostly disappear. 



t It cannot be admitted that the black X-shaped or starred spots are invariably due to the 

 influence of salt water, as we see them present in our strictly fresh-water grayling, ThyimUtis, 

 also salmon grilse reared entirely in fresh water have many more spots than the marine visitant 

 {see plates III and IV). While in Willoughby (p. 194) we find, " in Salmonum et Truttaruni 

 speciebus distinguendis nimium ne crede colori," and we may also apply the words of Ovid 

 concerning the Polvpus to these fishes, " Sub lege loco mutatqne colorem." 



2 * 



