LNTBODUCTION. 7 



have in many cases deservedly received names ; they will, however, 

 be treated as of subspecific value only, partly as giving a truer 

 idea of their real value, and partly because the evidence is so often 

 insufficient to show whether the forms are varieties or geographical 

 races, points which must be left to local workers to elucidate. 



The range in space given for many of the species will necessarily 

 be found very imperfect ; all the large collections in England have, 

 however, been consulted, to make them as correct as possible, and 

 all recorded localities are quoted except a few given by the older 

 authors which are certainly wrong, those that are considered 

 doubtful being indicated by a ? 



Transverse markings are described as bands and lines ; and 

 longitudinal as fasciae and streaks. 



Species of which specimens were not available, and of which 

 the descriptions are taken from those in print, are indicated 

 by a *. 



When the sex is not specified the descriptions, measurements, 

 &c. apply to both sexes. 



The following references are given : one to the original descrip- 

 tion, one to each synonym, one to the best coloured figure, one to 

 a description or figure of the larva, and one to Cotes and Swinhoe's 

 1 Catalogue of the Moths of India,' which must be consulted if 

 fuller references are wanted. 



Microscopic slides have been prepared of several genera in each 

 family, and the structural details are all taken from drawings 

 made by the author, elaborated and worked up by the artist. 

 Secondary and sexual characters are treated as of subgeneric value 

 tufts of scales on the legs, modified patches on the wings, fans 

 of scent-hairs, and such-like, besides being eminently variable, are 

 often present or absent in very closely allied species. The most 

 valuable of these characters is the development of pectinations, 

 serrations, cilia, &c. on the male antennae ; but if these are used 

 for generic distinction, we have the inconvenience of not knowing 

 to what genus a species belongs till we have the male. 



The development of secondary sexual characters sometimes dis- 

 torts the form to such an extent that the generic and even family 

 characters are entirely obliterated, as in the males of Patula and 

 Argiva, and the female is then the sex that is of greatest value in 

 showing affinity. The contrary often occurs, as in the wingless 

 females of Solenobia, Psychidce, Heterogynidce, and some Lyman- 

 triidce and Geometridce, these being cases of degradation sometimes 

 in connection with a parthenogenetic mode of reproduction. 



Starting from Micropteryos with its biting mouth-parts us the 

 nearest ally to the theoretical ancestor (x) of the Lepidoptera, we 

 may construct some such genetic tree as follows : 



