22 PREFACE. 



history of each species in order to designate it 

 hy the name applied to it by its first discoverer. 

 The rule adopted is to give priority to tJie fird 

 published description or to the first published name 

 accompanied by a recognisable figure, and to reject 

 all claims based upon the publication of a name 

 only, as these, if allowed, would inevitably lead 

 to doubt and inconvenience, and in the end 

 would afford opportunity for unfairness and 

 fraud. The date of the first publication of the 

 species is appended to the name of the work in 

 which it appeared. The operation of the rule 

 will restore to American authors many species 

 which were first described by them, but which 

 have long had a place in the works of MM. 

 Ferussac, Lamarck and Deshayes under the names 

 of foreigners who did not know them until after 

 they had been described in this country. 



It is one of the aims of this work to point out 

 the errors, and to supply the omissions, of those 

 and other distinguished naturalists ; but although 

 the author hopes to make his own work more 

 useful thereby, he is far from presuming that it 

 can bear a favorable comparison with theirs in 

 any other respect than in giving a more fuU and 



