747 
advances distally towards the anterior wing-margin, and so comes_ 
in contact with the fore-end of a still lighter bar, which begins in 
the area of III at the said margin, but takes such a sinuous course 
in a postero-external direction, that the dominion of III so to say 
curves up to that of Il. 
A similar feature can likewise be observed in another Sphingid, 
whose forewing-pattern agrees with that of nerd? in a remarkable 
number of points, viz. Dillina tiliae. Here the feature in discussion 
is seen in the anterior part of the external border-line of the dark 
central field, by which the forewing is so characteristically divided 
into a proximal and a distal light area, and which itself is broken 
up (either completely or nearly so) into a larger anterior and a 
smaller posterior portion by a constriction along the course of the 
second cubital vein. This constriction corresponds in position and 
character to the above-mentioned white zig-zag-line of nervi. 
That this explanation of the forewing-pattern of nerü is well 
founded, becomes especially evident when we compare it to that of 
nearly-related species, e.g. Aypothous (Moorn, Lepidoptera Ceylon, 
Pl. 83; Cramer, Pap. Exot. III pl. 285 D; Seitz, X 63a), layardi 
(Moore, Pl. 81; Seitz 63a‘), protrudens (Novara Exp. Zool. Il, 2, Taf. 
LXXVI, 7; Seitz X, 63b®), angustans (Nov. Exp. Zool. Bd. II 2), 
placida (Seitz, X 63a‘). 
But as the most remarkable patterns in regard to this feature I 
consider those of omissa and its congeners (miskini, anceus, sericeus, 
cunera), because here parts of the nerii-pattern are so to say pro- 
jected on that of Smerinthus populi, the latter appearing as if 
it were visible by transparency beneath the first. 
Groningen, October 1919. 
49* 
