260 MR. J. WATSON ON THE PLUMULES OR 



serrated costal margin of the upper wings^ easily felt by- 

 running the finger along the edge. A short time ago I 

 drew Mr. Hewitson's attention to them, expressing a wish 

 that they might be more correctly placed in a new genus. 

 Mr. Hewitson had some time ago separated this group in 

 his cabinet, and Mr. A. R. Wallace, who is at work on the 

 Pierida, has done the same ; and I was much pleased to 

 receive from him lately an inquiry respecting the absence 

 of plumules, showing that he attaches value to the subject. 

 He proposes to call the new genus Prioneris, from the saw- 

 like structure of the costal margin"^. The only other 

 species of Pieris which I have examined without finding 

 plumules are Agathon, Protodice, and Callidice; the 

 absence is very remarkable in the two latter, as their 

 allies Daplidice and Hellica are abundantly supplied there- 

 with. 



There is a group of this genus to which I did not allude 

 in my first papers, being then doubtful whether its scale 

 could be considered a plumule — that is, of a character serv- 

 ing for distinction ; such scales are very abundant on P. Ly- 

 cimnia, Flippantha, Isandra, and some congeners, showing 

 that these are perhaps all varieties of one insect. You will 

 see a figure of it on PI. I. fig. 6a; and great has been my 

 surprise to find a somewhat similar form in some members 

 of the Danaidse family, to which further reference will be 

 made ; these have not the bulb-and-socket apparatus. 



The interlinking of affinities, and the manner in which 

 Nature loves to repeat her works with variations, are 

 strikingly shown in the plumules generally ; and throughout 

 the difierent families there may be observed assimilations 

 of form existing in widely separated groups, just as is the 

 case in the insects themselves. 



* It is interesting to note that a similar serrated costa occurs in some 

 species of Papilio, of Charaxcs, and of Gonepteryx ; and these are all without 

 plumules. 



