WCP2977

[1]¹

ZOOLOGICAL MUSEUM,

TRING,

HERTS, ENGLAND.

February 23^rd 1910.

Dear Dr Wallace

The changing gloss which you refer in your letter² of Febr. 17^th is only found in a limited number of species. It is found in a number of species of Papilio allied to vertumnus² (of which cutora Gray in the Amazon from the ♂), for instance in culaces Gray, phosphorus Bates, lycimenes Boisd, [2] polygalas Feld, anchises, d., and others. When viewed obliquely, the black hindwing changes into metallic blue, which, I think, is the cause of these appearing a peculiar lustre above the "opalescent" spots. In this case the spots would be best decribed as phosphorescent, I think Ornithoptera magellanus Feld. (Philippines) has a similar lustre, but the wings resembles more a polished opal than phosphorus, these being no luminous cloud above the surface of the wing.

The [illeg.] Euselasia praeclara [3] Hew., from the Amazon, has the strangest gloss of all Lepidoptera. Here the gloss is a buffish yellow surface and therefore appears somewhat raised above the wing, but I should call it opalescent rather than phosphorescent.

Burgena chalybeata Roth., an Agaristid from the Bismarck Archipelago, may also be mentioned. Both its wings change on the upperside from black to blue, fiery red and opalescent.

The change observed in spatura iris is quite common among butterflies.

[4] I do not think that any researches have been published on the luminous sheen of these insects.

Believe me, | very faithfully yours | K. Jordan² [signature]