CHAPTER V. 



IDENTIFICATION, 



WITH the aid of our tabular scheme we ought to be able to find 

 the genus of any British fish without difficulty. Let us try 

 a few examples. 



Here is a flat-fish ; the mouth is not on the under surface, and 

 there is a gill-cover. That takes us at once past the first group. 

 Are its eyes to the left or to the right? To the left. Has it two 

 spines behind the left ventral ? No. Is its tail short or long? 

 Short. Are its scales large or small ? There are no scales. The 

 genus is Rhombus, and of the two species it can only be R. maximus, 

 the turbot. 



Here is a fish in which the vertical fins are continuous. That 

 takes us on to another group. Is its body truncated ? No. De- 

 pressed in front,' compressed behind, with a sucker between the 

 ventrals ? No. Tapering from a large head ? No. Riband-shaped ? 

 No. The body is long and rounded. Does the skin extend over 

 the gill-covers ? Yes. Has it pectoral fins ? Yes. It is one of the 

 eels ; but which ? Which jaw is the longer, the upper or the lower ? 

 The upper. The genus is Conger, and there is only one species. 



Let us try one with a heterocercal tail. Has it bony plates 

 along it ? No ; the body is without plates. Has it an anal fin ? 

 Yes. One dorsal or two ? Two. Is the first dorsal above the 

 interval between the ventrals and anal ? No ; it is over that between 

 the pectorals and ventrals. Is its head hammer-shaped? No; it 

 is conical. Has it a pit at the base of the caudal fin ? No. Is 

 its second dorsal fairly large, or is it much smaller than the first ? 

 Much smaller. The genus is Galeus, and there is but one species, 

 the tope. 



Let us take one with a homocercal tail. Is its tail at an angle 

 to the backbone ? No ; it is not Trachyptcrus. Is its body short 

 and stout and armoured ? No. Is it deep and compressed ? No ; 

 it is neither the opah, the dory, nor the trumpet-fish. Is it long and 

 slender ? Yes. Is it ridged with bony plates ? No. Are both 

 jaws prolonged into a beak ? Yes ; it is either Scombresox or Belone. 

 Has it any finlets ? No ; and consequently it is Belone, the one 

 species of which is the mackerel-guard, or gar-fish. 



Yet another. How many dorsals are there ? One complete, 

 and a series of spines representing one in front of it. Have the 

 spines any filaments ? No. Are there scales all along its side or 

 plates ? Plates. The genus is Gasterosteus, one of the sticklebacks, 

 for further particulars of which we refer to the chapter in which the 

 genera are sorted into their respective species, though from the 



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