Tank No. 10. 
67 
kingdom. We will only remind the reader that the "cuttlefish” are not 
really "fishes” in the zoological sense but mollusks, and that there are a 
few true fishes differing considerably from the usual form, such as the 
snake-like eels, the flattened rays and soles, and the graceful sea-horses. 
As the fishes, like the other animals, are arranged in the Aquarium 
so as to suit their various modes of life, we shall also arrange our remarks 
Fig. 117. Scyllium catulus , Fig. 118. Labrax lupus, 
t/e nat. size. f/ 6 nat. size. 
to illustrate the same. Scientifically the fishes are divided into cartilagi¬ 
nous and bony fishes respectively, but in both groups according to their 
habits we can distinguish Drift-fishes, that is such forms as are always 
or almost always swimming, and Bottom-fishes, which pass the greater 
part of their life lying on or even buried in the sand, or on the rocks. 
This distinction cannot, of course, be carried through quite consistently, 
as we find all sorts of intermediate forms. 
We will begin with the Cartilaginous Fishes, to which the Sharks, 
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