INTRODUCTION. XI 



By the dorsal and anal fins their lateral move- 

 ments are effected ; elevation and depression 

 are promoted by the pectoral ; the caudal or 

 tail-Jin propels them forward, the ventral 

 supports them when stationary; and many 

 are further assisted in rising or depressing 

 themselves by an air bladder. Numerous 

 facts disprove the opinion that the senses of 

 fishes are not acute. The eye of the trout, 

 fixed and immoveable as it is, sees from the 

 bottom of the river the minutest midge or 

 gnat as soon as it drops, and the lively worm 

 is taken with eagerness, when one that is 

 dead or diseased, is refused, as much pro- 

 bably by the exercise of the olfactory, as of 

 the visual powers. The scepticism now so 

 fashionable with regard to the virtues of cer- 

 tain oils used by old fishermen, is probably 

 erroneous, and it is not unlikely that the se- 

 baceous glands in the heron's legs are at- 

 tractive to fish. Nor are fishes without the 

 sense of hearing, although destitute of either 

 external conch or internal cochlea, for the 

 firing of a gun will cause the basking fishes 

 immediately to fall to the bottom. Their 

 taste is displayed in refusing certain mat- 

 ters, while others are taken with avidity: 

 neither are their organs of touch so obtuse as 



