370 PALAEONTOLOGY 



Types of a much lower degree of value are the 

 following : 



Any specimen of a species coming from the same 

 locality and zone as its holotype or syntypes is a 

 topotype. Topotypes can be indefinitely increased in 

 number by collecting, whereas there can never be more 

 than one holotype or lectotype, and never more than a 

 few paratypes or syntypes. 



A topotype recognized by the original author as be- 

 longing to this species acquires additional value thereby, 

 and is called a metatype. 



A specimen of a species described or figured by the 

 original or any later author at some subsequent date to 

 the original establishment of the species is a plesiotype. 



What a type-specimen is to a species a type-species or 

 genotype is to a genus: that is, it is a more certain 

 means of settling the application and extent of the generic 

 name than any verbal definition. 



If the author of a genus defines one particular species 

 as typical of the genus, that is the geno-holotype. 



If he only gives a list of the species which he considers 

 to belong to his genus, these are geno-syntypes. 



Out of a series of geno-syntypes a geno-lectotype 

 may be chosen at any later date, either by the original 

 author of the genus, or (with his permission, or after his 

 death) by any subsequent author. 



The collector of fossils who wishes to name his speci- 

 mens accurately will need to take much trouble in 

 hunting through works in which fossils are described and 

 figured. These works are of several categories. 



First, we have monumental works, mostly of rather 

 early date, which set out to describe and figure all the 

 fossils (or all of some great group of fossils) found in 

 some one country or State. 



Secondly, there are numerous smaller works, some- 



