31 



tudo quorundam Piscium ad speciem diversorum, qui 

 in situ Partium externarum semper, numero plerumque, 

 Figura et Proportione ssepe conveniunt." The genera 

 are recognisable by certain characters, which are of 

 such a nature that, by their aid, u the various fishes 

 belonging to different genera can be told apart and be 

 referred to their respective genera". 



As Artedi, both here and in several other places 

 in his writings, makes a point of the universal appli- 

 cability of the general statements which he enunciates 

 regarding Fishes, with which he is directly concerned, 

 we are justified in looking upon his reform work as of 

 the utmost import for the whole systematics of Zoology. 

 For instance, he remarks, with reference to genus-cha- 

 racters, that natural characters constitute "primum et 

 praecipuum Fundamenfum non solum Ichthyologise sed 

 totius reliquse Historian naturalis", and similar extracts 

 might be multiplied. 



With regard to the characters to be made use of 

 in delimiting the various genera, Artedi points out how 

 essential it is that they should be chosen judiciously, 

 for otherwise the classification will be of no practical 

 use from a scientific point of view; thus, the general out- 

 ward appearance is apt to be seriously misleading, as 

 the example of the tench and the lake-trout plainly 

 proves, for though they resemble one another fairly 

 closely in external shape of body, yet one of them be- 

 longs to the carp-genus and the other to the salmon- 

 genus. He also calls attention to the fact that the same 

 characters may have different systematic values in dif- 

 ferent groups, and that as a consequence it will not by 

 any means always be feasible to employ the same kind 

 of characters as distinguishing marks for congeners in 

 different orders; he illustrates his argument by adducing 

 examples. 



The next question taken up for discussion is which 

 properties of fishes lend themselves for employment as 

 genus-characters, and which do not. Artedi considers 

 that the best and most constant genus-character for os- 



