Eastern Pieridce. 313 



genus Tlujca form, with very few exceptions, a series vvliose affi- 

 nities for each other are very clearly marked. There remains 

 another small group of species which do not harmonize well with 

 any of the other forms, and which have been generally scattered 

 widely through the genus. The bond of affinity which brings 

 them together is to be found in the costal margin of the fore 

 wings in the males being distinctly toothed along its entire length, 

 forminrr a saw-like edge often visible to the naked eve. The 

 species which possess this peculiarity, now nine in number, are 

 found to agree closely in every other point of general structure 

 as well as in the form and texture of the wings and in their system 

 of colouration ; and I am informed by Mr. Watson that they have 

 another striking peculiarity in being quite devoid of the scales 

 termed plumules, which are present in the males of all other 

 members of the old genus Pieris. Such a combination of cha- 

 racters appears to me to indicate generic difference, and I accord- 

 ingly propose to form for them the genus Fr'toneris, of which the 

 type will be the Pieris t/iesfylis, Doubl. 



Tliere still remains in the genus Pieris, of which we may con- 

 sider our P. hrassicce to be tlie type, a considerable number of 

 species which agree very closely in structure, though they will 

 range under several types of form and colouration. Even from 

 these, however, two genera have been separated, neither of which 

 I heie admit. The genus Ajporia, Hubn., has been adopted by 

 some European Entomologists for Pieris cratcegi and its allies, 

 and it undoubtedly is a very distinct form from its European con- 

 geners. But when we see that, by means of P. hippia, Men., and 

 P. soracta, Moore, it is allied to such different-looking insects as 

 P. agalhon, Gray, and P. nabellica, Boisd., which evidently form 

 the fragments of an extensive natural group of species not differ- 

 ing in any important structural characters from the true Pieris, 

 we comprehend that it is more by isolation and a specialised facies 

 than by any generic peculiarity that these insects differ from their 

 nearest allies. The only character that can be so considered, the 

 short palpi of P. cratcegi, is not constant in the allied forms. 

 These constitute an Alpine and Arctic group of Pieris, and our 

 common species is a straggler beyond the range of its closest 

 relations. 



Wallengren has separated the African Pieris severina, Godt., 

 and its allies, under the name of Pinacopteryx, but the generic 

 character he has given would apply to many other species. The 

 only character by which these seem to me to differ from true 



