THE CANADIAN ENTOMOLOGIST. 79 



have the most complete, as far as it goes, accurate, and, for the style of 

 the work, the cheapest — in short, the best — work yet published upon the 

 Butterflies of North America. J. Fletcher. 



ON HEMARIS DIFFINIS, Boisd. 



BY A. R. GROTE, BREMEN, GERMANY, 



In my own collection I labelled a form in which a slight dentation of 

 the terminal band on primaries was perceptible (and which in this respect 

 agreed with Boisduval's figure in the Species General, and with Abbot's of 

 fticiformis) as H. diffinis. It differed from teftuis by a greater breadth 

 of band, a perceptible apical stain, a somewhat brighter or more yellow- 

 haired body. Whether this was Mr, Strecker's Aettira, I knew not, since 

 I was unacquainted with this author's work, having seen only his numbers 

 on occasion. H. tenuis is more purely a black and yellow species, with 

 no red ; it is the smallest and commonest of our Northern forms ; the 

 bands narrow, quite even, black ; the vitreous spaces seeming larger. 

 Undoubtedly it will be labelled diffinis, as, before we wrote, everything 

 was labelled diffinis or thysbe belonging to this genus. This genus is of 

 the class I have called p7-ogetie?-a, the species being near allied in all 

 stages. Our forms (although axillaris strikingly contrasts with tenuis) 

 are near together structurally ; they vary in one direction, viz., the gradual 

 increase of the apical red stain, of the width and dentation of the band 

 of primaries, of general bulk. But they are all outgrowths oi fuciformis, 

 so to speak. They are quite different from gracilis. This latter, though 

 very distinct, appears to me to be strictly congeneric with the European 

 bombyliformis, rather than with fiiciformis., to stand alone without near 

 alHes,- hence I divided it sub-generically to draw attention to its value as 

 compared with the tenuis series, among which the Californian forms which 

 I know, palpalis, thetis, range themselves. Quite American, and there- 

 fore certainly to be considered by themselves, are the forms I separated 

 under ffcetnorrhagia. The mission of Entomologists is to discriminate, 

 not to confound. If our categories are unstable, they may be corrected, 

 but inevitably they must be erected with precision to avoid the popular 

 error of confounding different looking insects under the same category 

 and under the same name. 



