INTRODUCTION. ix 



some distinguishing characters, which have been care- 

 fully pointed out by Prof. Zeller, Verh. z.-b. Ges. 

 Wien, xxiv. p. 444), the two previously mentioned 

 must be even more clearly entitled to claim specific 

 recognition. 



Under the name of (Edematophorus occidentals I 

 have ventured to include the two very different 

 varieties figured in Plate II. figs. 13, 14, partly on 

 the evidence afforded by a series of eight specimens 

 obtained on Mt. Shasta in August, which do not 

 vary among themselves, but appear to be exactly 

 equidistant between them, and partly because I have 

 other specimens from neighbouring localities which 

 are again intermediate in both directions between 

 the Shasta specimens and the two which have been 

 selected for illustration. 



Again, in the genus Lioptilus, the two varieties 

 of L. homodactylus, Walker, would have been suffi- 

 ciently distinguished from each other by the difference 

 in the colour of their heads ; but an intermediate 

 shade of colour is observable in the heads of some 



