FOSSIL FISH. 



419 



of the tail, as behind the gill-covers, while the contrary evi- 

 dently takes place in the fossil. The upper jaw, too, is much 

 shorter in the latter than in the former, which may be acci- 

 dental. There is also a slight difference in the form of the first 

 dorsal fin ; but, as to the rest, the resemblance is perfect. 



C. rhombus J De Blain. ; C. mesoleucus? Volta. This 

 fossil skeleton is equally well preserved, to enable us to decide 

 that the species from which it proceeded was not the analogue 

 of mesoleucus. In fact, it has not the prolonged muzzle ; and 

 the gill-covers, which are perfectly preserved, present no traces 

 of spinous radii. 



C. nigricans J Volta. The case is the same with the species ; 

 though there may be some approximation, the form of the 

 dorsal fin is entirely different. 



C. canescens, Volta. Nor can this approximation of 

 Volta''s be admitted. The first two rays which follow the 

 spines are infinitely more elongated in the living than in the 

 fossil species, and the form of the anal fin presents very 

 notable differences. 



C. saxatilis, Volta. Here there is more analogy than in the 

 majority of the foregoing. Perhaps, indeed, the identity is 

 perfect : the living species is found in Egypt. 



C, chirurgus, Icht. Ver. There is, perhaps, still more pro- 

 bability that this is the analogue of the living species. The 

 fossil, however, is more orbicular, that is, proportionally more 

 raised. Its dorsal fin is not so long, nor placed so low ; it has 

 fewer spinous rays ; and the anal fin, also a little different in 

 form, appears evidently situated further back. There is no 

 trace of the curved sting or spine in the fossil. 



C. ignotus, De Blain. ; C. macrolepidotus, Icht. Ver. 

 There is the utmost evidence that this approximation by Volta 

 is totally wrong. There is scarcely anything in common be- 

 tween the fossil and the living animal. In fact, the latter has 

 ten dorsal spines, the fourth of which is longer than the body ; 

 while, in the fossil, the rays of the dorsal fin, as well as those 



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