83 



gleaned during the previous hundred years. Yet, this is 

 what we were asked to do. Such species as Campto gramma 

 hilincata, TJura variata, Emmclesia nnifasciata, and Anticlea 

 hadiata, had been proved to belong to separate genera; yet 

 we find them all lumped back with another thirty-five species 

 into the one genus Hydriomcna. Again, we find the 

 Hydviomenidce made a separate and distinct family from 

 Sterrhidce, which contains such proved closel}- related 

 species as those of the genus Acidalia. Neuration to afford 

 useful characters must be corroborated where possible by 

 facts of the life-history of the species. If the grouping by 

 neuration is different from the grouping by life-histories there 

 is something wrong with our work. Meyrick's " Handbook," 

 notwithstanding the faults of a one-sided view, marked the 

 greatest advance that had been made by a study of the 

 veins. For the first time we have a working basis estab- 

 lished, for we find in the introduction an answer given to the 

 question, Which are the older, and which are the more 

 recent genera ? The three following laws are postulated : 



(i) No new organ can be produced except as a modifica- 

 tion of some previously existing structure. 



(2) A lost organ cannot be regained. 



(3) A rudimentary organ is very rarely re-developed. 



As Me3'rick truly remarks, monstrosities appear to offer an 

 exception to law, but monstrosities are not reproduced,'^ 

 and do not enter into a progressive or retrogressive develop- 

 ment of a species. The outcome of the laws is that the 

 genera and families with the fewest number of veins are 

 the most highly specialized, and those with the greatest 

 number are the most generalized. On these grounds Meyrick 

 made out the Ardiidcv to be the most highly specialized 

 family of the British Lepidoptera. From 1878 till the present 

 day the name of Meyrick stands out as the great exponent 

 of the use of neurational characters. 



Hampson, in his " Moths of India," placed the Sahirniidce 

 first without giving any reason for so doing. The SaturniidcB 

 have this peculiarity, however : that in certain genera, parti- 

 cularly in Attacm, the cell of both fore- and hind-wing is 

 open, a character that is very general in the highest family 

 of the RJiopalocera, the Nymplialidcc. Hampson, in his later 

 work, the " Lepidoptera Phalaina," the first volume of 



* The breeding of many hernnaphrodites from a single batch of eggs by 

 Mr. A. Harrison appears to contradict this statement. But such cases are so 

 excessively rare as hardly to be reckoned as a phenomenon of Nature, and 

 hermaphroditism, although a phase of monstrosity, is something special. 



