XX PEE FACE. 



On the subject of Nomenclature it may be remarked 

 that the oldest names have been adopted in most instances, 

 unless a different one has been sanctioned by general use. 

 As the author is of opinion that in common parlance there 

 is no occasion to name the sub-genus, when speaking of 

 any particular species, he has not thought it necessary to 

 change the names of species which are the same as those 

 of the sub-genera to which they belong. 



The synonyms will be found to embrace references to 

 some of the principal writers, more especially those in our 

 own country, who have treated of the different Classes, or 

 of any subordinate group, or any particular species. These 

 references have, in every instance, been examined person- 

 ally by the author. To facilitate the inquiries of such 

 persons, as may wish to examine for themselves on this 

 subject, a complete list has been annexed of all those 

 works, with their several editions, which are quoted, either 

 for the synonyms, or for any other purpose. 



It has been thought proper to annex two distinct in- 

 dexes, one containing the Latin, the other the English 

 names. No pains have been spared to render them as 

 complete as possible. It is believed that every name and 

 synonym, in the above two languages, occurring in the 

 body of the work, will be found in its proper place. 



It now only remains for the author to express his 

 acknowledgments to those friends who have assisted him 

 in this undertaking. To Mr. Yarrell in particular, he begs 

 publicly to return his sincere thanks for the able help which 

 he has experienced at his hands, and such as alone has 

 enabled him to complete the work upon the plan first 

 contemplated. This help has been especially felt upon the 

 subject of the British Fishes. Had it not been for the 

 very liberal manner in which that gentleman offered him 



