( IVf. ) 



alterntioiit;. In many jiapers, of whicli 1 mention only Ila;^en, Iris VII., Letzner, 

 Kiijer Sch/esiens, Scliilsky, Ka/er Preusseiis, the opinion has been expressed and 

 carried out that the same name can be used several times for varieties of the species 

 of a genus ; thus Hagen proposes the uames Pupilio hewitsoiii var. sumutrana, 

 P. neptunus var. siimalrana, P. cloant/ius var. sumatrana. The theoretical reasons 

 in favour of this system are considerable; practically, however, the system leads, not 

 to stability, but to instabilily of nomenchiture. What Hagen regards as varieties 

 Other people will treat as species — P. hewitsoni var. sumatrana Hagen has, indeed, 

 previously been described by de Nicdville as a distinct species, P.petra Nicev. — and 

 then the insects will have to be renamed ; other scientists come afterwards again to 

 the opinion that the insect is nevertheless a variety only and must be caUed with the 

 first uame. Thus a change of names will bo in mauy cases the cousetiueuce of that 

 system of nomenclature. As there is no general character which enables one to see 

 at once whether a form is s])ecifically distinct or is only a variety, and as, therefore, 

 very often a certain form will be treated by some entomologists as sj)ecies, by others 

 as variety, and as the way to the truth is in many cases still very long, the same 

 name dare not occur twice in the same geuus, uo matter whether the name be applied 

 to species or varieties. And it is advisable even to avoid a uame which already 

 occurs in an allied genus for a new form ; the genera, or the views of entomologists 

 ill res))ect to the delimitation of the genera, are changeable, and what now stands 

 in two or more allied genera will often come in future under one generic term, and 

 then the forms bearing the same uame will have to be renamed (compare Kirby's 

 Catnlogue of Heterorrra and Hamjison's Moths of Jndi(i). 



The law of strict priority, without which a stable nomenclature will never be 

 obtained, must also be applied to " composite " species, i.e. it must be applied to 

 such cases where several species or varieties of a geuus have received the same name 

 by the same author. If the different forms which are erroneously treated as being 

 the same are described one after the other — it cannot be of any consequence whether 

 the descriptions appeared at the same time, under the same heading, or at diti'ereut 

 places — it is not difficult to decide to which insect alone the respective name must 

 be restricted. As Linn^ described an Indian Papilio as demole.u.<i in IToS, andau 

 African one under rhe same uame iu 1764, it is evident that the name u'i di'inoleus 

 must be applied to the Indian, not to the African butterfly. In 17<i4 Linne 

 characterised two insects as P. panthous, first a black and white coloured Papilio as 

 one sex, and then, as the other se.\, a black and yellow coloured butterfly. We have 

 here two P. E. panthous L. described one after the other, though under the same 

 heading and number ; the first characterised Pa])ilio has certainly the priority, as it 

 stands before the other. If, however, the description of the composite species does 

 not help us in this or a similar manner, we must accept the identification of that 

 author who is the first to deal with tlie insects in question after tlie jiublication of 

 the common name. Thus we liave treated all the composite species and varieties : 

 Troides panthous (L.); Troides helena (L.); Papilio lorquinianus phiUppus \Vall. ; 

 P . demoUus L. ; etc. 



Wlicn we had come to a decision about the correc! name of a Pa()ilio, and had 

 learnt I'rom the literature what is known of the insect, there remained the diliicuh 

 question to solve whether this butterfly be the type of a distinct sjiecies or a varietal 

 form of another Papilio. It is usually said that the specific distinctness or non- 

 distinctness of a Papilio or other animal very often de])ends on the individual views 

 of an author, and that there is uo general parting line between species and varietal 



