378 ZOOLOGY. 



ment of the ribs, this air bladder is acted on, so that by the 

 quantity of air being diminished, the specific gravity of the 

 fish alters according to circumstances ; but fish swimming 

 near the bottom have no air bladder such as the skate, sole, 

 turbot, and eel; and sometimes this bladder is membranous 

 and vascular, so as to resemble a lung. 



In a small number of fishes, as the flying fish, the pectoral 

 fins are much extended, so as to permit the animal to leave 

 the waters and to fly to a considerable distance; and some 

 by the same means travel on the land, and even climb up 

 trees. 



Whilst speaking of the organs of motion in fishes, we 

 cannot omit mentioning a singular apparatus which some of 

 these animals have, by means of which they adhere strongly 

 to a foreign body : it is a flattened disc covering the top of 

 the head, composed of cartilaginous plates, moveable, and 

 directed obliquely backwards (Fig. 387). Fishes of the 

 genus echeneis are the only ones which have this kind of 

 organization, and the species found in the Mediterranean 

 has been long celebrated under the name of remora (Fig. 

 388). Its natural history has been overloaded with fables, 

 and the power of suddenly arresting a ship in its course was 

 ascribed to it. A species closely resembling the preceding is 

 very common in the waters around the Isle of France, and it 

 is said that on the coast of Caffraria it is employed in fishing 

 for other fishes. A line being attached to its tail it is launched 

 in pursuit of others ; so soon as it becomes attached to them 

 the fisherman, by means of the string, gains possession of 

 both. 



484. The life of a fish is occupied almost wholly in pro- 

 viding for its subsistence and escaping its enemies ; its senses 

 and faculties seem obtuse and limited ; it exercises no known 

 industry, and seems to be without any remarkable instinct ; 

 its brain is small, and the organs of sense imperfect. The 

 brain does not fill the cavity of the cranium, there being 

 found within it a spongy fatty mass, particularly in the adult 

 specimen. The lobes composing the brain are placed in a 

 file, one pair behind another, namely, the olfactory lobes, 

 the hemispheres, the optic lobes, and the little brain, and 

 behind that the lobes belonging to the medulla oblongata. 

 The sense of touch seems to be exercised only by their lips 

 and by the feelers surrounding the mouth (Fig. 381 b) ; their 

 taste must be imperfect, considering the structure of the 



