455 
This broadening in a caudal direction makes the impression, that 
an oblique line of separation runs across the forewing from tip to 
root, dividing it into an antero-interior lighter field and a postero- 
exterior darker one. Calling this line the V-diagonal (because the 
lines of the two wings in expanded attitude form the letter V) we 
may state, that this V-diagonal-design occurs in numerous Lepi- 
doptera of various families, though always as a secondary modifi- 
cation of the original pattern of transversal bars. In the group of 
Chaerocampine Sphingides, which 1 hope to discuss in a future 
communication, this feature is particularly striking. 
We find it however in the same way in the families of Hepia- 
lidae, Noctuidae and Geometridae, and likewise in numerous Micro- 
lepidoptera. In the overwhelming majority of these cases the V- 
diagonal-pattern is restricted to the upper side of the fore-wing; 
the underside showing the primitive pattern of transversal bars. 
As specially striking examples may be mentioned the Noctuid 
genera Ophideres, Nyctipao and Emmondia, the 
Bombycid genus Eupterote, as well as many Geometrids. 
The species of Ophideres give rise to the remark that the 
separation of the forewing-area in an antero-internal and a postero- 
external part, brought about by the V-diagonal-design, in many 
species e.g. O. tyrannus, salamia and fullonica (comp. 
Seitz III, Pl. 66) seems to be connected with the resemblance of 
the entire forewing-design to a withered leaf, this likeness bringing 
the said species under the category of the leaf-imitating Lepidoptera. 
We have to deal here once more with such a feature, as can 
show itself in many different shapes, and therefore in its real 
character is evidently independent of the importance it may 
in some particular cases possess for the establishment of protective 
resemblance. 
It further results from the mutual comparison of different species, 
that the contrast between the anterior and the posterior part of the 
wing-surface may be very different in quality as well as in quantity. 
In some species the forepart is light, the hindpart dark, in others 
they are nearly alike. In O. materna a transversal design of 
Cossid-markings (traits effilochés Borkn, Rieselung Eimer) spreads 
over both parts; in the male the V-diagonal is present, in the 
female absent, while on the contrary an A-diagonal-design is partly 
developed as a light-coloured-streak. For besides the V-diagonal an 
A-diagonal can be distinguished, running from before and inside to 
behind and outside in an oblique direction over the wing-surface, 
often it seems to possess some connection with the division of the 
30 
Proceedings Royal Acad. Amsterdam. Vol XXII. 
