THJS NAMING OF SPECIES 431 



that particular combination of generic and specific 

 name was never used before. 



555. By common consent, also, the name first 

 given to a plant must always be used to desig- 

 nate it; and all subsequent names are cited as 

 synonyms. While this rule of priority is a most 

 important one in the naming of plants, there are 

 exceptions to it. For example, the rule that the 

 same name shall not be used for two plants, 

 takes precedence. If an author should inadver- 

 tently make a name which had been used before, 

 his name may be set aside and a new one sub- 

 stituted. If an author considers that any species 

 is in the wrong genus, he may transfer it to an- 

 other, and a new combination of names is the 

 result ; but, by custom, he must use the same 

 specific name in the new genus unless that name 

 is already in use in that genus. 



555o. Thus, the wild erab-apple is generally referred to the 

 genus Pyrus, and it is known as Pyrus eoronaria. But there are 

 some authors who would divide Pyrus into several genera, one of 

 which is Malus, the apples. The crab then becomes Malus eoro- 

 naria. 



5556. The specific names may be common adjectives, as eoro- 

 naria, agreeing in gender with the name of the genus; proper ad- 

 jectives, as Americana, Smithiana, also agreeing with the genus; 

 proper names in the genitive, as Smithii ; or substantives, as La- 

 brusea, used in apposition to -the generic name. Some botanists 

 write the proper names and substantives with a capital initial, 

 but others use no capital for specific names. 



555c. Binomial nomenclature, as now used and understood, be- , 



