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The Student will please to observe the following 

 Notes. 



1. For simplicity, I have occasionally omitted 

 in the definition of families, genera, &c., those 

 characters which are not needful in the discrimi- 

 nation of British specimens. 



2. Species occasionally occur in which some one 

 or more of the generic characters are wanting, 

 while yet the preponderance of characters shows 

 it to be rightly located. Nature will not bend to 

 our systems. 



3. In general, a character once given must be 

 understood as belonging also to following genera 

 in the same family, until it is distinctly contradicted 

 or modified. 



4. The mark (?) placed before the name or 

 initial of the genus, indicates an uncertainty 

 whether the species truly belongs to that genus. 



5. The mark (?) placed after the name of a 

 species indicates that there is some doubt whether 

 the specimen or specimens found on the British 

 shores really belonged to that species. 



6. The proper name set after the name of each 

 genus is the name of the naturalist who first de- 

 fined its characters. 



7. The mark = signifies " equivalent to," or 

 " synonymous with ; " and is used when a generic 



