i88 THE POPULAR SCIENCE MONTHLY. 



tened from side to side, and tapering to a fine extremity. In the 

 smallest gars it was longer than the fin below, in the older it was 

 shorter, while in the adults no trace of it appears. 



These two tails have very different movements. The lower, cor- 

 responding to the caudal fin of the ordinary fish, is used in three 

 ways. When the little gar is in a gentle current, and Avishes not to 

 be carried downward, the fin is made to execute a series of undula- 

 tory movements, such as have been described by Prof. Agassiz re- 

 specting the dorsal fins of young pipe-fishes, etc., and such as the 

 writer has observed with the long dorsal fin of Atnia. 



This tail is also strongly flexed to one side, as with ordinary fishes, 

 in order to change the course. And it is rapidly moved from side to 

 side for all sudden and rapid locomotion, as when frightened. 



The movements of the filament were first described by Prof. 

 Agassiz, and he called attention to them upon several occasions. But 

 his descriptions are very brief, and, upon one point, seem to require 

 modification. 



The filament is in almost constant vibration. Occasionally, when 

 the gar is at rest, and perhaps also when it is turning, or rapidly 

 swimming, the filament is not used. But usually the vibrations are 

 so rapid that the tip of the filament is invisible, excepting as an in- 

 distinct blur. Generally, it is directed backward and slightly up- 

 ward, but at times it is bent to one side, or elevated to nearly a right 

 angle with the body, the tip all the while in constant vibration. 

 Those who have watched the tail of an irritated rattlesnake, or even 

 of a common striped snake, under strong excitement, may form a 

 pretty correct idea of the nature of this movement. It was charac- 

 tei-ized by Prof. Agassiz as " involuntary ; " and so it may be regarded, 

 since its rapidity is such as to preclude the idea of a separate volition 

 for each movement. But the gar, evidently, has entire control of the 

 vibrations; for they are more or less rapid at different times, and are 

 occasionally intermitted ; the position of the whole filament is changed 

 at will; finally, the muscular bands upon each side of the cartilagi- 

 nous rod, v/hich runs througli the filament, consist of the striped va- 

 riety of muscular fibre, as are the other voluntary muscles. 



This is all the wi'iter has seen of living young gar-pikes. But the 

 explanation of the peculiar double tail is furnished by some still 

 younger specimens, the smallest of which is shown, enlarged, in 

 Fig. 9. 



These little gars were scooped out of the Red River, near Shreve- 

 port, Louisiana, in the spring of 1871, by a lad only ten years old, who 

 had heard the writer say that he wished for very small fishes. At 

 that point these young gars were then as abundant as minnows, as 

 easy to catch, and commercially as worthless. All of them are less 

 than two inches long, and among them are two about three-fourths 

 of an inch in length. These last are not only much smaller than any 



