Reviews — Kners Classification of the Ganoids. 429 



III. — Professor Kner's Classification of the Ganoids. 



Considered by Dr. Christian LUtken, Assistant Zoologist in the Museum of the 

 University of Copenhagen. 



THIS little paper adds to the already well-earned renown of its 

 author as an Ichthyologist; and the subject of which it treats 

 is so important, that the attention of Palaeontologists should be 

 drawn to it through the pages of the Geological Magazine. 



Professor Kner announces his conviction that the order of Ganoids 

 is not a true natural assemblage ; he considers it to be rather opposed 

 to the development of the true natural system. The argument 

 which he puts forth in support of his statement, is that none of the 

 characters which have hitherto been proposed for the order, are 

 precise or exclusive ; in fact, it is not, so to speak, properly circum- 

 scribed at all. He criticises the definitions given to the Ganoids by 

 Agassiz, J. Miiller, Heckel, Pictet, and Owen, showing that the 

 characters proposed are either such that their existence cannot be 

 established in the fossil specimens, or else that they are such as 

 they possess in common with fishes of other orders, or lastly, such 

 as only occur in a more or less limited degree among the various 

 genera commonly regarded as Ganoids, — they are, in short, neither 

 precise nor absolute. 



But I think that Prof. Kner goes too far when he claims that 

 every systematic division (especially the higher) shall be founded 

 on precise and absolute characters, such as are without exception, 

 and which they have in common with no other class, order, etc. 

 We must accept the natural divisions as nature herself has estab- 

 lished them, and define them as well as we are able. I do not 

 know if Prof. Kner will be capable of giving a single precise and 

 absolute character of a Saurian, a Fish, a Snail, or a Crustacean ; 

 but I doubt it very much, and I do not see why the poor Ganoids 

 should be more severely treated than the most natural divisions of 

 the animal kingdom. I heartily agree with Prof. Kner when he 

 writes, "I cannot recognize the order of Ganoids as a natural group 

 at least, not with the limits which are at present given to it, 

 and I believe that its limits are to be drawn in a narrower and 

 sharper manner than hitherto." But he goes further, and states that 

 the fossil Ganoids are not only the ancestors of the living ones, but 

 of all later and recent Teleostei; and that those characters, which 

 have been regarded as determining a Ganoid, are simply a common 

 stamp of antiquity impressed upon those primeval types. ("They 

 do not represent a single definite order, but rather the whole amount 

 of development of the recent Teleostei ; they are the expression of 

 the law of progressive evolution in the class of fishes, whose 

 principal types and great families are already represented among 

 them by the means of prototypes.") Besides, Prof. Kner gives no 

 clue for subdividing the Ganoids and classing them with the more 

 recent families, of which they are the presumed prototypes. The 



1 [Betrachtungen iiber die Ganoiden als natislische Ordnung. Sitzuugsberichte d. 

 k. k. Akad. d. Wissench. Wien. Eand liv., 1866.] 



