i;v It. J. Tii.r.v \i;n. 



123 



families of Lepidoptera. Both these scales are remarkable for 

 the following series of characters : - the scalloping of the distal 

 border; the large number and consequent closeness of the par- 

 allel longitudinal stria?; the presence of a number (.f thickened 

 or coarsened stria?; the presence of cross-striolation; and its 

 attendant character, the presence of pigment granules in the 

 scale itself. It should be further noted that the membrane of 

 the wing in Ahtesarchcea is quite transparent, while that of the 

 other Mir.ropler;iyid(P, always has more or less brown pigment 

 deposited within it. Thus the beautiful metallic effects found 

 in this family are due to the combination of pigment in the 

 membrane with striation of the scales; but in the non-metallic 

 Afuesarchcea the whole colour-producing apparatus is located in 

 the scales. 



We have now to enquire whether the scales of Mnesarvhuea 

 show any close resemblance to those of any known family of 

 Lepidoptera. In Text fig. 11, h, I give a drawing of the hitherto 

 undescribed scales of Prototheora (Suborder Homoneura, family 

 1'i-ufot/icwidrr), which will be seen to be exactly comparable with 

 the medium-width scale from Mnesarchcea figured in Text-fig. 1 0,6. 

 The only difference between the scales in this family and in 

 Mnesarchcea is that the type of scale shown in Text-fig. 1 1, A, is 

 the broadest to be found in the I'rototheoridie, and it is inter- 

 spersed with a number of scales that are not scalloped at the 

 distal end, but merely lanceolate, or even oval. Cross-striolation 

 is present in all the scales of this family, and, indeed, in those 

 of every family of Lepidoptera, as far as I know, except only in 

 the four genera of Aficropteri/yidte already mentioned. 



Two types of scale from the family Hepialidaz are shown in 

 Text-fig- ll,yj g, the first from Ckaragia, the second from Peris- 

 sectis. Kellogg(5) supposed that the presence of coarsened strife 

 was peculiar to this family, since it had not been found in any 

 other. We now see that this type of striae is to be found in all 

 three families of the Homoneura, but not in any known Hetero- 

 neura. The scales of Hepialidce appear to be distinguished by 

 their flattened distal borders, as contrasted with the scalloped 

 border of the scales of Mnesarchcea and Prototheora, and the 



