446 



Note 1. In all other cases the generic name is regarded 

 as "nomeii nudum". 



Note 2. The fact that a generic name is "nomen praeoccu- 

 patum" is held not to affect the validity of the generic group with 

 reference to the proceedure indicated below for the determination of 

 types. Experience shows that confusion is best avoided by this method. 



The object of fixing the type of a genus and of the methods of 

 determining the type, (A) by elimination, (B) by citation; is to 

 restrict, as early as possible in the history of a genus, the area within 

 which the type need be sought for. 



Definition of Type. 



The type of a genus consists of a single species which serves as 

 a Standard of Comparison for determining the characters which 

 are to be connoted by a particular generic name. 



a) By Elimination or Exhaustion and by Restriction. 

 Rule 1. The type must be represented by one of the species origi- 

 nally included in the genus when the generic name was 

 first bestowed. 



- 2. A species once removed from a genus to a new generic 



group is no longer available as the type. 



- 3. A generic group may be restricted to one or more species, 



at any time Avhen a new genus is being founded which 

 includes one or more of the original species. 



- 4. A generic group may be restricted by the quotation of the 



generic name accompanied by one or more of the original 

 species, with the term "sensu restricto", and the species 

 left in by the process of elimination, or isolated by restric- 

 tion, are alone available for service as the type. 



- 5. When a single species alone has been left in, or isolated, 



this is regarded as the type. 



b) By definite citation. ' 



1) At the time when the genus was first founded. 



2) At a time subsequently to the founding of the genus. 



1) Rule 6. When the founder of the genus has definitely cited any 

 single species under the terms, "typ", "typus", "type" 

 or "typical" — the species thus referred to is regarded as 

 the type of that genus. 



- 7. When the founder of the genus specially refers to the figure 



of a species in connection with the generic diagnosis, this 

 is also regarded as a definite citation of the type. 



