114 '^^^^ Scottish Naturalist. 



dilutata (PL I. A Fig. 4 and 5) is distinctly and sharply toothed, 

 while in the other two species the same part of the harpago is 

 merely angulated. 



It is evident, therefore, that dilutata is most decidedly a 

 species distinct from the other two. In them there is a great 

 similarity of structure, but the difference in formation, which I 

 have pointed out above, though slight, seems to be constant, 

 and taken along with other differences, appears to show that 

 autwnnaria ^cadi JiUfjrammaria are both good species, and such 

 I have little hesitation in pronouncing them to be. 



It will be observed, of course, that this structure exists only 

 in the males, and that some other points must be found, not 

 only by which the females may also be separated, but by which 

 all specimens can be determined without dissection. I there- 

 fore give descriptions of each of the species. 



O. DILUTATA. F.-w. scarccly glossy, greyish-white, more 

 or less distinctly tinged with brown, with numerous transverse, 

 wavy, darker lines and bands ; second line indistinctly and 

 roundly angulated near the costa ; central spot usually very 

 indistinct in the male, more distinct in the female ; h.-w. 

 scarcely glossy, whitish with a brown tinge, and with one or 

 two indistinct lines parallel to the hind margin. 



Expanse of the wings in the $ 34-41 mm. (16-19 lines), 

 in the $ 34-36 mm. (16-17 lines). A series of measurements 

 resulted as follows : — four specimens 34 mm., four 36, two t^Z, 

 one 40, and one 41. 



Any variation in colour that I have seen is rather towards a 

 paler form, and a less decided brown tinge. I have seen no 

 infuscated specimens. . 



O. AUTUMN ARIA. F.-W. distinctly glossy, slightly more 

 pointed than in dilutata, greyish white with a silvery-grey tinge, 

 with numerous transverse, wavy, darker lines and bands ; 

 second line more distinctly and acutely angulated near the 

 costa ; ceijtral spot usually distinct but sometimes rather 

 obscure by the space between it and the second Hne being 

 infuscated ; h.-w. glossy, whitish, with a silvery-grey tinge, 

 hind margin frefjuently with a more or less distinct broad pale 

 grey band. 



Expanse of the wings in the ^ 34-40 mm. (16-18^ lines), 

 in the ? 35-41 i^fini- (16-19 lines). A series of measurements 

 gives this result : — one specimen 34 mm., one 35, four T^d, five 



