122 THE CANADIAN ENTOMOLOGIST 



Catocala, the European are fewer in number and comparatively better 

 marked and distinct, standing farther apart from each other. The harden- 

 ing process by which each species becomes more isolated in time, seems 

 to have reached a more final stage with the European species of Catocala, 

 etc. I have orginally compared the European C. fraxini, with the 

 North-American C. relida. I found differences in size and color between 

 the two " representative " species, on the whole so slight as to warrant 

 the belief that the two were derived from a common ancestral stock. We 

 must seek for this ancestral stock in the tertiary, when its range probably 

 extended over Northern or British America, and Siberia. A character 

 which is distinctive of the present European species, is the dull blue 

 median band of the secondaries. Now, I found, and first recorded the 

 fact, that, in certain examples of the American form which has the band 

 white, a faint blue edging to the band was found. This was a reversion 

 to the original color in all probability. The tendency of color to become 

 brighter and lighter in America, owing probably to atmospheric or 

 climatic conditions, is thereby exemplified. The specimens of C. relida, 

 which have the forewings dusky, are also probably instances of this 

 reversion. A form belonging to this group of the genus has been also de- 

 scribed from California. It is doubtful, as yet, whether this can be con- 

 sidered a distinct species. The variation of the North-American forms 

 has led to the publication of a number of names which, in some instances 

 at least, are not properly founded. This " hardening into species " seems 

 to be a natural process by which we may conceive the forms to become 

 gradually more peculiar, different from their surrounding allies. At length 

 the time may arrive when they disappear by extirpation, laaving given rise 

 themselves to other species, through variation, their species-offspring 

 surviving them. 



From a classificatory point of view, the genus Catocala can hardly be 

 held as " typical " of the Nocttia. fasciatce, the more geometriform group 

 of the family. Rather is Pheocyma ( Homoptera) to be thus considered ; 

 the wings are unicolorous, and the darker rivulous markings extend over 

 both pairs, while the secondaries are more or less exposed in repose. In 

 Catocala they are hidden, and Lederer sees no necessity for any sub-family 

 division. Probably the terms are to be used stritftly for the convenience 

 of students. The tibiae are often spinose in these wide-winged genera, 

 and this character, not unusual in the family, the Catocalince have in com- 



