INTRODUCTION. XI 



1. When the author of a new generic name only mentions 



one species as being included in the genus, that 

 species is obviously the type by monotypy. 



2. When an author uses for a new generic name the 



specific name of one of the species included in the 

 original genus, that species is obviously the t} r pe. 

 For instance, the type of the genus Regulus Cuvier 

 is obviously Motacilla regulus of Linnaeus. 



3. Where an author distinctly designates as the type one 



of several species included by him in a newly con- 

 stituted genus no confusion can possibly arise. 



4. When this has not been done and the type of a genus 



cannot be determined by monolypy or tautonymy, the 

 first author who designates the type of the genus 

 must be followed. In nearly all cases this was done by 

 George Robert Gray, whose work has already been 

 referred to. Some writers have suggested making 

 the first species mentioned the type of these genera, 

 but it has been found that this rule if carried out would 

 involve a large number of alterations in our present 

 generic names and would lead to great confusion. 

 The same difficulty is found with the method of 

 " elimination." In this case where a genus contains a 

 number of species, as each reviser successively removes 

 some of these to other or new genera a point is 

 reached when only one species is left. This, then, 

 constitutes the type. It can be easily imagined that 

 such a method is full of pitfalls and uncertainties, 

 and it has now been completely abandoned. 



5. In the case of Linnsean genera it is often possible by 



an examination of the quotations given by Linnseus, 

 and also by referring to his original authorities, to 

 find out which species was the original possessor of 



