^PPEISTDIX L. 



REPORT ON ICHTHYoLoM 



\',\ Vi:<>v. Theo. Gill. 



Smithsonian Institution, 



Washington, December 1, 1S<><>. 



Sir: I have the honor to forward to you the report on the ichthyology of your 

 expedition, which I have been requested to prepare. 



Although few species of fishes were obtained, they are of much interest Most 

 of them have been fully described in the accompanying- report, even when not new, 

 as in the case of the species which is now called Platijgohio communis. As all the 

 groups to which the respective species belong are in some confusion and not well 

 restricted, I have been compelled to examine the history and nomenclature of not 

 only the genera to which they are referable, but of the allied ones. As in almost all 

 the cases, such genera have been limited in a different manner and considerable modi- 

 fications introduced, I have always given the full generic characters, founded on a 

 personal examination, or a careful perusal of the descriptions of all the known species 

 of the genera. This I have considered to be the course most advantageous, under the 

 circumstances, to science. 



The classification which I have here followed is that which I have proposed and 

 published in the Proceedings of the Academy of Natural Sciences of Philadelphia. 

 It may be considered a modification of that of the illustrious and learned Johannes 

 Miiller. whose recent death has been so much mourned by naturalists ; it differs from 

 the Miillerian classification in the very different acceptation and restriction of the 

 orders and suborders. 



The investigations which have been undertaken in the preparation of the report 

 have been pursued in the Smithsonian [nsrirution; and to the power of availing myself 

 of the excellent Library and Museum of the Institution, such value as the report may 

 have is due. 



I am, sir, very truly yours, 



Theo. Gill. 



Capt. J. H. Simpson. 



