40 
SOME FACTS ABOUT FISHES. 
BY THE EDITOR. 
R ECENT researches, and especially those explorations of the 
deep sea which have been systematically carried on of late 
years, have brought to light numerous interesting facts in rela- 
tion to fishes. Some phenomena previously altogether unsus- 
pected have come to our knowledge, whilst others have been 
shown to be of far more general occurrence than has hitherto 
been supposed. In the present article we propose to call 
attention to one or two prominent points brought out by late 
investigations. 
Anything like a true metamorphosis is of very rare occurrence 
among fishes. Indeed, the only change which can, to a certain 
extent, be compared with the metamorphosis of the Batrachia, is 
presented by the Lampreys ; and even in them the change from 
what we must call the larval condition to that of the adult, is 
by no means so great as that from the tadpole to the perfect 
frog or newt. The lampreys, as most people are aware, are 
eel- shaped, scaleless fishes of very low organization, destitute of 
paired fins, having on the head a pair of eyes and a single 
nasal aperture, and on each side behind the head seven aper- 
tures belonging to an equal number of branchial sacs. The 
mouth, which is situated quite at the anterior end of the 
animal, is formed by a shallow, circular cavity, at the 
bottom of which the actual opening is situated, having 
a peculiar horny tooth above and another below it, and a similar 
armature upon the tongue, which occupies the aperture. Besides 
these the inner surface of the funnel-shaped cavity has nu- 
merous conical teeth, which are really the horny coverings of so 
many small papillae ; and these are of use to the animals when 
attaching themselves by suction to other objects. In fact, they 
adhere by their mouths to the stones at the bottom of the 
streams which they frequent, and thus, without much bodily 
exertion, they resist the action of the current (from this habit 
