89 



and its congeners have a much less powerful flight, while 

 Lcucophasia sinapis and its allies fly along lazily almost like 

 slow-flying geometrid moths. Compare the neuration in 

 these species. It is very considerably different. Colias has 

 vein 10 absent and ii present. Enchloe has both present. 

 Leiicophnsia has them present, but they are in a totally 

 different position and are stalked with 6, 7, and 8, and all 

 given off beyond the cell. In all these, as well as in all 

 other Pierines. there is, however, a constant character, and 

 that is, that all have two submedian veins to the hind-wing. 

 Here there is at least one character to diagnose the family 

 with. They, also, all have the forelegs fully developed in 

 both sexes : so this, in conjunction with the neurational 

 character, can be used in defining and diagnosing the 

 family. How valuable such characters are one only appreci- 

 ates in dealing with foreign species which have not the 

 remotest resemblance to any of the Pierines of which we 

 know the life-history, perhaps, in its entirety. The remark- 

 able South American ^enevd., P event e and Archonias, m all 

 the species, and Disnwrphia in many of its mimetic species, 

 would have been impossible of location without rehing on 

 these constant characters. 



There are some families which are comparative!}' limited 

 in extent, and there are some that have very few species, 

 and one even but a single representative as in Endroinidce, 

 which has as sole representative Dimorpha versicolora. Noto- 

 dontidcc, Zygcrnidcr, and the wholly exotic Ceratocampidcc, 

 Euptcrodidcc, and Megalopygtdcr are small limited families : 

 and, as far as we know them, the habits of the species within 

 these different families are very uniform. The Nctodontida: 

 contains species that fly onl\- at night, or at dusk, and the 

 ZygcsnidcB contains species that only fl}' in the bright sun- 

 shine; and the flight is almost invariabh' a slow, buzzing 

 flight. These families, as well as the other exoric families 

 named, show very little variation within the limits of these 

 groups, but for that very reason the characteristics of the 

 family are of the utmost use in diagnosing a species, which, 

 perhaps, has the characters of one of these families, and 

 beyond which we know absolutely nothing. 



Another very limited family is the Drepanidce. But in this 

 family, even in Britain, we have species with very different 

 habits of flight. Cilix spinula has a very feeble and slow 

 flight, but the species of the genus Drepana, such as D. 

 hinaria and D. cidtrarin, are \'ery different, and fly briskly, 

 the latter even in the hot afternoon sunshine. Compare 



