FINS : THEIR USES. 57 



creased greatly in size, and apparently at the 

 expense of the caudal fin, which they gradually 

 superseded. Undina, whose remains occur in the 

 rocks of the Lower Lias, had similar false and 

 true tails, the false tail being functional. 



CHAPTER VI. 



FINS : THEIR USES, AND WHA.T THEY TEACH US. 



It seems almost like presumption to think of 

 drawing attention to, or in any way describing, 

 the fins of fishes. They are such obvious, and we 

 think, at first, such inseparable appendages, that 

 no fish is complete without them. "What fisher- 

 man is there who could not discourse upon fins 1 

 If he be a fisherman of any experience, he will 

 have much to say concerning their ofi*ensive 

 possibilities, in some fish at any rate ; or he w^ill 

 tell how useful, or sometimes undesirable, they 

 are in live bait fishing, how some are soft, some 

 hard, how there may be few or many, and so on. 



But all are not fishermen of experience, and 

 there are doubtless many who have never realised 

 what an immense amount of interest is to be 

 found in tracing out the modifications which the 

 fins undergo in diff'erent fishes, or what may have 

 been their origin. 



To these inexperienced our remarks are now 

 addressed, and for their benefit we will begin at the 

 beginning. The fins of fishes, then, are divisible 

 into two kinds : (1) The median fins — the fins 



