THE CANADIAN ENTOMOLOGIST 69 



again, mulleolata emerges a month earlier than citrata, namely in 

 June, while the latter appears in July and August. The genitalia 

 also show it to be distinct from citrata, the terminal spines being 

 nearly three times" as long and much stouter. The species, there- 

 fore, should be considered as distinct and so listed. Hulst's types 

 are not in ver>^ good condition and more or less rubbed, so this is 

 probably the reason why the older authors regarded it as truncata. 

 I have specimens from Mr. Fernekes from Tacomah, Washington, 

 and from Mr. Blackmore and Dr. Dyar from Victoria, B.C., and 

 the Rocky Mountains. It is evidently a rare species in collections, 

 but probably the characteristic locality has not been found. 



Mulleolata Hulst has several striking forms which correspond 

 to the forms of citrata and should be described, so that they may 

 be understood. I may perhaps be criticized for naming aberrations, 

 but I feel that we cannot correctly understand the limits of variation 

 unless we do so. In many species it is absolutely necessary to do 

 this, as different species have corresponding forms and would 

 otherwise be confused with one another. I think it unnecessary 

 to go as far as the European specialists do, but certainly every 

 distinct form should have a name, and both Dr. Bastelberger and 

 Mr. Prout concur in this view. The difhculty is to avoid splitting 

 the forms too finely, as in the case of truncata and citrata. It is 

 better to take a conservative view of them where confusion might 

 arise, e. g., in the case of the white-banded forms of citrata and 

 mulleolata, or the black-banded forms of the same, or in the case of 

 many of the species of Hydriomena. 



We may next consider the forms of mulleolata Hulst which 

 seem to be worthy of names. 



Dysstroma mulleolata Hulst, ab. sobria, nov. 



Expanse 36-39 mm. 



This is the black-banded form of mulleolata Hulst, correspond- 

 ing to ab. immanata Haworth of citrata. The central band of the 

 fore wings is solid black with no markings or whitish spots visible. 

 The wing pattern is otherwise the same as in normal mulleolata, 

 except that possibh- the brown is a trifle more yellowish extra- 

 discally. The aberration sobria can be easily recognized by the 

 solid black central band and the date of appearance. Apparently 

 this is one of the rarer forms, as other specimens show the transition 



