1565 
Moreover, as every entomologist is aware, a great number of 
insects, especially in primitive groups, both among the recent and 
the ancient ones (for carbonic Insects see Hanprirscn, pl. VII 
XXXIV) possess a stately array of transverse veins along the anterior 
margin; thus lending greater probability to the conclusion to which 
we were forced by the comparison of the three orders. 
One more point deserves consideration. 
Where we assumed a close connection between the original wing- 
design of Lepidoptera and Trichoptera and the nervural system of 
their ancestors, or rather the coloured margins, which accompanied 
the nervures, the question rises: may not the reticulate colour-pattern 
found in both orders (as well as in a few Diptera) and especially’ 
developed in Cossids, point to a former reticular arrangement of 
nervures, such as is still found in many Neuroptera and other 
primitive orders ? 
In that case the reticular colour-pattern would have a primitive 
character, still more so than the system of transverse striae, and 
point to an even more remote ancestor. The occurrence on one and 
the same wing of motives of different ancestral age is in itself by 
no means impossible: our Vanessas and a great number of other 
butterflies supply striking examples of this combination. 
Nevertheless I am inclined to consider the reticular colour-pattern 
as a derived one for the following reasons : 
1. It is only found in Cossids, not in other primitive families. 
2. It is almost wholly absent in the higher families of Lepidoptera. 
3. It is easily transformed into the pattern of internervural trans- 
verse markings. 
4. We should be obliged to go back to the oldest insects, the 
Palaeodictyoptera, to meet with forms, with which it could be brought 
into connection; because the Megasecoptera, which are generally 
regarded as the ancestral forms of the oldest Panorpata, were already 
in possession of a regular system of transverse nervures. 
To sum up, we must regard the primitive colour-pattern of Lepi- 
doptera as a relic of the more complete system of nervures which 
their ancestors possessed ; a remnant of the numerous, colour-bordered 
transverse nervures, which later on became obliterated. Though this 
heritage in some later forms has totally vanished, swept, so to say, 
from the surface of the wings, in others it has acquired an even 
greater prominence, being susceptible to different adaptations, not 
always in its original simple form, but modified in different ways 
and various directions. 
Groningen, 11 March, 1916. 
