ZOOLOGICAL NOMENCLATURE. 365 



when the latter genus came in the course of time to be divided 

 into two, it was incorrect to give the condemned name Monau- 

 lus to one of the portions. To state this succinctly, 



§ 6. When two authors define and name the same genus, 

 both making it exactly of the same extent, the later name 

 should be cancelled in toto, and not retained in a modified 

 sense.* 



This rule admits of the following exception : — 



§ 7. Provided however, that if these authors select their 

 respective types from different sections of the genus, and 

 these sections be afterwards raised into genera, then both 

 these names may be retained in a restricted sense for the 

 new genera respectively. 



Example. — The names (Edemia aiuZ Melanetta were originally 

 co-extensive synonyms, but their respective types were taken 

 from different sections which are now raised into genera, dis- 

 tinguished by the above titles. 



[No special rule is required for the cases in which the later of 

 two generic names is so defined as to be less extensive in sig- 

 nification than the earlier, for if the later iucludes the type of the 

 earlier geuus, it would be cancelled by the operation of § 4 ; 

 and if it does not include that type, it is in fact a distinct 

 genus.] 



But when the later name is more extensive than the earlier, 

 the following rule comes into oepration : — 



\_A later name equivalent to several earlier ones is to be cancelled.] 



The same principle which is involved in § 6 will apply to § 8. 



§ 8. If the later name be so defined as to be equal in extent 

 to two or more previously published genera, it must be can- 

 celled in toto. 



Example. — Psarocolius, Wagl., 1827, is equivalent to five or 

 six genera previously published under other names, therefore 

 Psarocolius should be cancelled. 



If these previously published genera be separately adopted (as 

 is the case with the equivalents of Psarocolius), their original 

 names will of course prevail ; but if we follow the later author 

 in combining them into one, the following rule is necessary : — 



* These discarded names may, however, be tolerated if they have been after- 

 wards proposed in a totally new sense, though we trust that in future no one 

 will knowingly apply an old name, whether now adopted or not, to a new genus. 

 (See proposition q. infra.) 



