595.78 390 
Ill 
The Neuration of Rhopalocera 
IVEN the theory of evolution, structural characters of living 
insects, whether embryological or imaginal, afford means of 
classification according to the persistence among them of various 
degrees of specialization from primaeval forms of structure, 2.e. the 
links of continuity of specialization in any direction. The neura- 
tion of the wings is a structural character common to all Lepidoptera 
—a few apterous females excepted. Hepialides and Micropterygides, 
perhaps the most ancient groups of Lepidoptera now existing, have 
more wing nervures than any other group and associate the Lepi- 
doptera with Trichoptera; series of gradations in modification of 
neuration in different directions more or less connected (less con- 
nected, perhaps, among ancient than recent groups), may be 
observed everywhere among existing Lepidoptera; thus reduction in 
the number of nervures, or alteration in the position of certain 
nervures, connect generalized (ancient) and specialized (recent) 
forms of neuration; as a matter of observation, I believe that, 
nervures once lost, or the position altered, neither has ever been 
regained—hence the different series of gradations. 
Fore and hind wings corresponding, the neuration may be referred 
to as follows :—Costa=upper margin. (1) Subcostal nervure. (2) 
Radial system =nervure with branches. (3) Median system = 
nervure with branches (nervules). (4) Cubital system = nervure 
with branches (nervules). (5) Anal nervures=several simple 
(unbranched) separate nervures. 
In this paper I propose mainly to refer to the neuration of the 
forewings, and possibly shall not enumerate all the nervures of the 
wings to save unnecessary details. 
Cossids, so far as I know, cannot be considered in any way 
related to the Rhopalocera, except by connections too remote to 
trace ; they retain a neuration relatively more ancient than that of 
any group of Rhopalocera. 
It may be instructive to compare the Cossid form of neuration 
with the several more or less. definite forms representing several 
groups of genera in the Rhopalocera, and I may here say that by the 
term group I mean an assemblage of species which may be associated 
upon a given pattern of wing neuration, or a distinctly connected 
modification of the same. In a recent instructive paper upon the 
“ Classification of the Day Butterflies,” published January and Feb- 
ruary 1898 in Natural Science, Dr Radcliffe Grote has given details of 
