66 MR. J. WATSON ON CERTAIN SCALES 



relative sizes of the plumules are various_, always^ however^ 

 about the same in different individuals of any one species. 

 The smallest or shortest are about 5-iooths of an inch 

 in length, and the largest or longest about i-iooth, in- 

 cluding the pedicle and bulbs. 



According to the modern arrangement of Doubleday, 

 Westwood, and Hewitson, the family " Pieridse " consists 

 of 16 genera; and in 7 of them_, viz. Euterpe j Pieris, 

 Anthocaris, IdmaiSj Thestias, Hebomoia, and Eronia, I have 

 discovered plumules^. There are several distinct types of 

 plumules, generally more or less running into one another ; 

 but each species possesses its own peculiarity, with diversity 

 sufficient for identification, while in each individual of the 

 same species there is always the same form of plumule. 

 These, therefore, must afford to the scientific entomologist 

 a valuable test in the determination of closely allied species, 

 and it is probable that they may serve to form congenial 

 natural groups and subdivisions in some of the genera. 



It is remarkable that the peculiar and well-known 

 plumule of Pieris Rapes should prevail, in a generic and 

 very similar form only, also in P. Napi, P. Cruciferarum, 

 and P. Gliciria (the first two European, the third North 

 American, and the fourth Chinese). These insects are of 

 close afiinity in other respects ; and in other instances con- 

 geniality of plumule is found in nearly allied insects. 



The figures 20 and 21 deserve particular notice, as ex- 

 hibiting a form which appears to be peculiar to the genus 

 Euterpe. This form may perhaps be considered a test for 

 that genus, and I believe that it has not been noticed or 

 figured before. 



The most remarkable and beautiful form of plumule, 

 now for the first time observed, as far as is known to the 

 writer or others to whom it has been shown, is that found 



* The examination extended over about 200 species ; and I found plumules 

 in all the male specimens, with three exceptions. 



