( 439 ) 



normal form of the species. Even if the physiological difference is accompanied by a 

 morphological difference, the variety cannot be considered a species as long as some 

 of its offspring are of the normal form ; A and B are not specifically distinct as long 

 as A produces B, and B produces A. 



II. Romanes's definition * is as follows : — 



"A group of individuals which, however many characters they share with other 

 individuals, agree in presenting one or more characters of a peculiar and hereditary 

 kind, with some certain degree of distinctness." 



This definition, if the words "and hereditary" were left out, would be based 

 solely upon the presence of morphological difference, " Evolutionists," says Romanes, 

 " have more and more grown to lay stress on the hereditary character of such 

 peculiarities as they select for diagnostic features of specific distinctness. Indeed it 

 is not too much to say that, at the present time, evolutionists in general recognise 

 this character as, theoretically, indispensable to the constitution of a species." f Our 

 objection against the word " hereditary," which does not " supply exactly that objective 

 and rigid criterion of specific distinctness " which we necessarily require, is two- 

 fold :— 



1. There are characters of an hereditary kind which are not specific. Indeed 

 many of those peculiarities of individual varieties which regularly appear in every 

 brood are hereditary, but do not make the individuals which exhibit them specifically 

 distinct. Among the individuals o{ Papilio S(irpedon,X to give an illustration, appear 

 specimens (in New Britain legularly) which have one or two additional green spots 

 on the forewing ; in specimens from the Solomon Islands additional green spots 

 are always present ; as for certain reasons we consider Papilio sarpedon to be the 

 descendant of a species with a greater number of markings than sarpeiiojinowhas, the 

 presence of such additional markings we have to explain by the assumption that these 

 markings are inherited from the ancestors. We observe here restricted inheritance 

 of a peculiar character in the individuals from various parts of the Indo-Australian 

 regions, and constant inheritance of that character on the Solomon Islands. Not- 

 withstanding that it is an hereditary character which distinguishes the respective 

 individuals, these specimens are not specifically distinct from those individuals which 

 are devoid of that character. 



2. Specific characters are not unrestrictedly hereditarj'. It is a well-known fact 

 that the various forms of some polymorphic species of butterflies are so distributed 

 that the species is polymorphic in one, monomorjihic in other districts. PapAlio 

 aegeu,s has a number of different /e?na/e-forms in New Guinea, the Aru and Key 

 Islands, while in Australia there is only one kind of female. Papilio c/y^ia is remark- 

 ably dimorphic in India in both sexes — the varieties are called clytia-iorm. and 



* Romanes, Darwin and After Darwin II. 1805. p. 231. 



t Ibid. 



X In this article I have given the names of species ami varieties without jidding the " author" for two 

 reason?. (I) The original meaning of a name has mostly changed, its application h.aving become restricted 

 or extended. The reference to the original author, therefore, would give us quite an erroneous idea about 

 the extent in which the name is used in this article. Various writers apply the same nauie with the same 

 original author to different forms of Li'jjidojttera ; hence it is necessary, in order to avoid confusion, to say 

 precisely in which sense a name is hero made use of. (2) As it is the contents of a name anti not the name 

 I have to deal with, the mere annexation of an author's name to the specific or varietal name would not 

 convey to the reader any idea about the meaning of the n.ime ; it is, therefore, necessary to give a reference 

 to a book where the respective form has been figured or sufficiently dcscribcfl. Instead of giving the 

 reference behind each name, I .-mnex to this article, for the sake of simplicity, an alphabetical list of the 

 species and varieties with the necessary references. 



