96 
Psyche 
[March 
differences can hinder the recognition of such biologically interesting 
species as those of the Lethe eurydice group. Despite abundant mu- 
seum evidence of sympatry, these species went unrecognized for 
twenty years after Chermock (1947) was unable to find genitalic 
differences between them. 
As usually happens with sibling species, recognition on biological 
grounds has led to discovery of morphological characters hitherto 
overlooked. These, however, are of a magnitude which would not 
be considered diagnostic of species in most groups of Lepidoptera. 
In fact, the genitalia seem to be among the most conservative 
characters in Lethe. Chermock found only very minor genitalic 
differences between L. portlandia and L. creola Skinner in the 
other American species group, and circumstantial evidence suggests 
that portlandia itself is really a pair of (largely allopatric) sibling 
species. Many Asiatic Lethe we have examined also show only 
slight differences among themselves and from their close American 
relatives. We consider it likely that what we are calling Lethe 
eurydice fumosa may also prove specifically distinct when its biology 
