Meykick.— On New Zealand Geonietrina. 53 



Larva with 10 (rarely 12) legs, three pairs of abdominal legs being 

 usually absent. 



A very well-defined and interesting group ; sometimes but erroneously 

 regarded as a single family, though it certainly comprises several. This 

 error has probably been due to Guenee, who established on superficial 

 grounds families which he could not define, and thereby caused an impres- 

 sion that no accurately definable families existed. I cannot pretend to any 

 certainty in my views of the families hereafter defined ; they may be 

 capable of further subdivision, or require partial amalgamation ; they are 

 however natural and accurately limited as regards New Zealand species. 



The following considerations on the process of development of the group 

 will justify the main outline of my scheme of classification. The ancestral 

 form of the Geometrina must have had 12 veins in the forewings, 7, 8, and 

 9 on a common stalk, the rest all separate ; and 8 veins in the hindwings, 

 all separate, and vein 8 free. This is the only form from which all existing 

 types could have originated. Taking first the hindwings, there are two 

 main types at present predominant ; (A) in which there are 7 veins, 5 and 

 6 separate, and 7 not anastomosing with 6 ; and (B) in which there are 8 

 veins, 6 and 7 stalked, 8 anastomosing with 7. These form the two prin- 

 cipal subdivisions of the group ; it will be seen that (A) differs from the 

 type by the loss of a vein (normal vein 5 which is obsolete, existing only as 

 a slight fold), and (B) by the stalking of 6 and 7, and anastomosing of 8 

 with 7. Probably, therefore, the hindwings of the ancestral form were 

 relatively broader than in either of these, since both changes are such as 

 would be likely to result from a contraction of space. This difference of 

 method indicates unmistakeably that the development of the Geometrina has 

 proceeded on two distinct main branches, the types of which will be found 

 to correspond with the Ennomidas and Larentidce respectively, as I have 

 defined them. Comparing the forewings of the same types, it will 

 appear that in the Larentidce vein 10 always anastomoses with 9, and 

 11 with 10, whilst in the Ennomidce they are often separate ; in the 

 Larentidce also vein 11 often coincides wholly with 10 on lower portion, 

 so that it appears to rise from the upper margin of a simple areole, or 

 even from 9 above areole ; this structure, which obviously implies a 

 greater remoteness from the type, is hardly ever found in the Ennomid®. 

 In the Larentidce, therefore, the single areole resulting from this latter 

 modification marks a later development, and the first three sections of 

 that family are of more recent origin than the other two. So also the 

 Acidalidce, which have this same character, are later as a whole than the 

 Larentidce, from which they differ by vein 8 of the hindwings tending to free 

 itself from 7, a reversionary but more recent development. Instances of 



