IV PKEFACE. 



" 6. A Collection of Mexican Freshwater Fi .hes, purchased of 

 M. SaUc. 



'* 7. A Collection of Marine Fishes, made at Amoy (China). 



" 8. A Collection of Marine and Freshwater Fishes from the New 

 Hebrides, purchased of Mr. MacgUlivray. 



" All these Collections contain so many interesting forms, either 

 entirely new to science, or previously not represented in the British 

 Museum, that I cannot forbear directing attention to the great 

 service which may be done to science by collecting fishes, in what- 

 ever country or sea an opportunity may occur. If we look at the 

 large accessions to ichthyology during the last fifteen years, we may 

 well conclude that not one-tenth of the existing species are known. 



" I would remark, that some authors, who have adopted genera as 

 defined by me, have misunderstood mo, if they have thought, that 

 the species, by which a genus is headed, is to be considered as the 

 typical one, A serial arrangement of the species is the most natural, 

 and it ought always to be adhered to as far as possible ; therefore I 

 generally commence a genus with that species which has some 

 relation to the preceding genus, placing the more aben-ant forms, or 

 those which are allied to the following genus, at the end ; and in all 

 such cases the typical species occupy the centre of the series. 



" Finally, I return my best thanks to my friend the llev. R. T. 

 Lowe, for supplying mo from his MSS. with detailed accounts of 

 many species examined by him at Madeira." 



JOHN EDWARD GRAY. 



iiritisli Museum. 

 .Time 1, 18G0. 



