PREFACE. 



Dh. Gunther observes, — " This volume contains the Pharyngogimthi 

 acanthopterygii and the Anacnnthim of MlUler. In the preface to 

 the third volume, I have expressed my doubts whether the Orders 

 established by that great anatomist are natural groups of fishes ; and 

 I fuUy share the opinion of those who do not consider the coalesced 

 pharjTigeal bones as a character of sufficient importance to unite 

 acanthopterous and malacopterous fishes into one Order. Placing 

 the structure of the fins above that of the pharjmgeals, I have 

 changed the name of Pharyngognathi acanthopteri into Acanthopte- 

 rygii pliary iigognathi. 



" The Anacanthini coincide essentially with the MaJaeopterygii 

 jw/ulares of the old authors, and they apjiear to me to be a very 

 natural order. The diff'ereuce in general appearance between a Cod- 

 fish and a Sole, indeed, is great, — so gi'eat, as to induce some ich- 

 thyologists to consider them as representatives of distinct Orders ; 

 but the absence of symmetry in the latter will be seen to be the 

 only constant character on which such an opinion can be founded ; 

 and this character is but little developed in the higher-organized 

 Pleuronectidcv, as in Psettodes. In this genus the want of symmetry 

 is nearly entirely limited to the position of the eyes, which are on 

 the right side in one half of the specimens of the same species, and 

 on the left in the other. On the other hand, the Gadoids and Pleu- 

 ronectoids agree in the great development of the dorsal and anal 

 fins, in the position of the ventrals, and in the increased number of 

 caudal vertebrag. 



" No general account of the Chromkles and of the Anacanthini has 

 been given for the last fifty years, and at that time onlj" a small 

 number of species were known. Therefore, although I believe that 

 this volume will be particiilarly useful to zoologists, I must ask their 

 indulgence for the imperfection of a work in a field which hitherto 

 has been so nuich neglected. The total number of species in this 



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