CHAPTER III. 



SORTATION, 



'"PHERE is no better way of knowing a fish than by a personal 

 * introduction, in which a sufficient acquaintanceship is made 

 to enable it to be recognised whenever and wherever it may 

 chance to be met with. But as an introducer is not always 

 available, and there are over two hundred and fifty fishes claimed 

 as British, it is evident that to know them by name another means 

 must be adopted. Let us, therefore, take a familiar species, and, 

 by ascertaining what it is not, discover what it is. 



In doing this, we need not at the present stage restrict our- 

 selves to the systematic distinctions which, in many cases, concern 

 themselves with internal structure invisible without dissection. To 

 begin with, let us avail ourselves of external characters, and, later 

 on, use the systematic grouping to confirm our diagnosis. Here, 

 then, is a fish, an ordinary fish, with nothing eccentric about it 

 in colour, shape, or fins, a fish that is known in every kitchen, 

 and comes to table with little alteration in its natural appearance. 

 It is not a flat fish, but, as the term flat-fish is, as a rule, restricted 

 to fishes like the sole and turbot, and does not include the skate and 

 its allies, which are also undeniably flat, let us say that its body is 

 vertical and not horizontal, the reference being to the position 

 in the water of the middle section when fully grown. 



As we have lighted on these horizontal bodies, we may as well 

 spend a few minutes with them, noting at the outset that they 

 are divisible into two groups : 



1. Those like the sole. 



2. Those like the skate. 



In the second group, both eyes are on the upper surface, the 

 mouth is on the under surface, and instead of gill covers like those 

 in our example, there are mere slits. 



In one species on the British list, which happens to be the 

 only representative of its genus and family, these slits are lateral, 

 as they are in the sharks; in fact, this is an abnormal sort of 

 shark, a peculiarly ugly animal unmistakable under any circum- 

 stances, with a broad, flat body tapering gradually into the tail, 

 the eyes very wide apart, and the paired fins large enough to be 

 compared to the wings of an angel or the cowl of a monk, whence 

 it is known as the angel-fish or monk-fish (Rhina squatina). 



With Rhina out of the way, we are left with the rays, of which 

 the skate is the commonest kind. These have the gill openings 



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