ON A NEW CLASSIFICATION OF TUB RHOPALOCERA. 77 



members of the difercnt gentes between themselves. This fact indi- 

 cates that the process of differentiation is (1) to a great extent, 

 brought about within the range of the gens itself, and (2) exhibits, in 

 this respect, a very high degree of energy ; the energy, however, being 

 unequally strong in the different gentes. 



Notwithstanding these divergences in the various gentes, some re- 

 markable parallels exist in the process of differentiation, one of 

 theui consisting, as we have seen, in an obvious tendency to the ob- 

 literation of the distal and the peripheral cones, and, at the same time, 

 to the further development of the proximal ones. Another parallel- 

 that also takes place independently in the different gentes, is the 

 general tendency for a proximal swelling to be differentiated. It is 

 also a very noticeable fact that this condition of things occurs, so far 

 as I am aware, neither in the Heterocera^^ — at least, not having the same 

 significance — nor in the Hesperidae, generally referred to the 

 Rhopalocera, but exclusively in the gentes of the remaining or true 

 Rhopalocera, and in every one of them. 



In my work, quoted above, I have pointed out that each different 

 gens of the true Rhopalocera is referable to a similar primitive and 

 fixed type, not only Avith regard to the structure of the basal-fleck and 

 the scale-covering of the palpi, but also in several other characters of 

 moderately great taxonomic value ; further, that these gentes also 

 exhibit certain parallels in the differentiation of other characters, being, 

 so to say, directed by a similar tendency. Such parallels occur, like- 

 wise, only in the true Rhopalocera. These facts indicate that the 

 gentes of the true Rhopalocera (to which I do not refer the llt'spcridae) 

 have a common origin, a conclusion which is confirmed by several 

 other characters discussed in my work. In these parallels we find an 

 illustration of the statement made by Chapman, that " of similar 

 structural developments taking place independently in different families, 

 the common inheritance is not of the structure itself, but of a tendency, 

 or at least a capacity, to develop it."f We can, further, conclude that 

 the different gentes, originally standing comparatively close to each 

 other — as they all descend from the same primitive type — very early, 

 i.e., long before the specific characters had become differentiated in 

 any of them, had taken an independent line of development. In 

 consequence of this, it may be considered that the different gentes, if not 

 simultaneously, at least shortly after one another, have branched off" 

 from the common stem. 



(To be concluded). 



* In the genus Castuin, the basal-fleck appears to be slightly swollen. This 

 swelling, however, cannot be directly compared with those of any llhopalocerous 

 group. 



t " Notes on Butterfly Pupa:, with some remarks on the Phylogenesis of the 

 Rhopalocera," Entom. Record, vol. vi., No. 6, 1895, p. 130. 



:]§>RACTICAL HINTS. 



Field Work for March and April. 



By J. W. TUTT, l-.E.S. 



1.— The sickly-looking plants of dock and sorrel found along the 



slopes of Folkestone Warren, on the sea-face of the cliffs, give larviu of 



.SV.sm cltii/sitli/oniiis in early April. The presence of a larva may be 



readily discovered by the mines and frass in the root-stocks. Plant 



