370 A HISTORY OF FISHES 



drawn, for there are certain lowly forms of life which might equally 

 well be described as animal or vegetable. The accompanying 

 diagram (Fig. 133) illustrates these divisions, and represents a 

 mere fragment of the taxonomic tree of living organisms which 

 is intended to show the systematic position of a single fish, the 

 Common Sole {Solea solea). 



The question of nomenclature is an important one, and 

 unfortunately there is still considerable diversity of opinion as 

 to the correct scientific name to be applied even to our com- 

 monest food-fishes. It may well be asked why it should be 

 necessary to give scientific names at all. The reason is that 

 vernacular or common names, although convenient, are by 

 no means precise, and are frequently used in a very loose 

 manner. The same name may be given to two or more totally 

 different fishes in different parts of the country or in various 

 regions of the world; or, as is even more common, the same 

 species may be known by quite different names in various 

 localities. The name "whiting," for example, is not only 

 applied to the well-known food-fish of the Cod family (Gadus 

 merlangus), but also to various kinds of fresh- water fishes. 

 Conversely, the following names, among others, are all used 

 for the Sea Trout {Salmc trutta) in various parts of the British 

 Isles, while the non-migratory members of this very variable 

 species have received as many vernacular names again : Orange 

 Fin, Black Tail, Phinock, Salmon Trout, Truff, Scurf, Sewen, 

 Bull Trout, Grey Trout, and Round Tail. The names of Peal 

 and Bull Trout are used in some parts of the country for the 

 Trout {S. trutta), but in others to the Salmon. Another good 

 reason for the use of scientific names is the fact that of the 

 fifteen thousand odd species offish known to-day probably less 

 than half have a common name in any language. There are 

 nearly a hundred species of Cichlids in Lake Tanganyika alone, 

 but very few of them are distinguished by the natives under a 

 particular name, and the same species will perhaps be given 

 one name by one tribe and a totally different one by another. 

 It is agreed, therefore, that, in order to obtain precision and to 

 avoid any chance of confusion, it is necessary to give every 

 species of fish a scientific name. In the words of Dr. Regan, 

 the name of an animal "is a clue to all that is known or that has 

 been recorded in literature about its structure, habits, economic 

 importance or anything else; without the correct name we are 

 in the dark and the conclusions we arrive at may be founded 

 on erroneous grounds." It not infrequently happens that two 



