I HAVE not seen in any entomological work an attempt to explain the well-known peculiar character of the wings of the “Plume Moths” (Pterophori). They depart so thoroughly from the rest of the Lepidoptera in having the wings cleft into so-called feathery “plumes” (although retaining the microscopic scales characteristic of their order), that we may be certain so marked a type must have been evolved along definite lines and for specific reasons. One species (Agdistes Bennetii) may be regarded as the first stage in the differentiation of these insects; and from this species we have successive modifications in the number of “plumes” up to Alucita polydactyla, where the ordinary wings are split up into no fewer than twenty-four.