91 



both function and position, vein 5 of the fore-wing is so 

 constant as to be of great utihty in diagnosing a noctuid 

 species. Vein 5 of the fore-wing is always nearer 4 than 6. 

 It is never from the centre of the discoceUular, and never from 

 the upper portion of it. If this vein were from the middle of 

 the discoceUular, one would suspect the species to belong to 

 the NotodontidcE, and if it were from the upper portion of the 

 discoceUular, and nearer vein 6 than the middle, one would 

 suspect the insect as, perhaps, a geometrid, as that is a very 

 constant character of the latter famil}^ : only in such aberrant 

 species as Macaria notnta, M. litiirata, Venilia macnlata is it 

 from the middle of the discoceUular. The fore-wing is 

 much more stable in its structure than the hind-wing, and 

 several characters, such as those mentioned, have never yet 

 been proved to be wrong by a complete knowledge of the 

 life-history. The neuration of the fore-wing does, however, 

 vary, and sometimes considerably, within the family. 



In the GeometridcE there are many species that form a 

 simple areole or small secondary cell, such as Acidalia 

 avcrsata, Cataclysnie virgata, and the species of the large 

 genus Enpithccia, or, as we should now call it, Tephroclystia. 

 Others have a double areole, such as in the genera Mclauippe, 

 Enimclcsia, Cidaria, etc. But a much larger number have 

 no areole at all. In man}' families the fore-wing remains 

 constant, while the hind-wing varies enormously. The 

 SyntomidcE and Arctiidce vary very little in the fore-wing, 

 while the hind-wing is excessively variable. Many species 

 of these two families have, accompanying a very modified 

 neuration, a very specialized outline of wing. Unfortunately, 

 where the variation is greatest, such as among many exotic 

 forms, we have least information of habits. But while in 

 Brazil this year I was astonished at the entirely altered 

 habits of the different SyntouiidcB taken. The flight of 

 Trichiira, for instance, was not in the least like the flight of 

 any other species of Syntomids that I had previoush- seen, 

 but was like that of the fossorial wasps, which are never 

 absent in the tropics of the New World. Again, the gaudy 

 Coreura atavia was not suspected of being a Syntomid ; its 

 broader wings and slow flight were the very antithesis of the 

 quick motion of TricJmra dixanthia, or Trichura grandis. 

 One might almost mention such cases by the score. Species 

 of SyntomidcB may be like wasps, bees, flies, beetles, bugs, 

 and even like butterflies, and if these groups in themselves 

 have different modes of flight, how exceedingh^ variable 

 must the Syntomida: be, which embrace a large selection of 



