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Art. LXV. — Observations on Species and Varieties. 

 By William Bentley, Esq. 



The difficulty of distinguishing species among British Lepidoptera 

 is generally acknowledged, in consequence of having to take specific 

 characters partly from the colouring of the wings, and in many cases 

 wholly so ; this in some measure accounts for our having in our cabi- 

 nets so many varieties named as species. There are indeed close affi- 

 nities among many that resemble each other in general appearance, 

 but are really distinct well-defined species. It is to the former that I 

 wish to direct the attention of your readers, and shall take for exam- 

 ple the genus Agrotis ; for the latter, I shall only give two examples, 

 1st. Graphiphora brunnea and tristigma; these species resemble each 

 other much, and I have seen them named in cabinets as one species, 

 but when examined they will be found to differ in their antennae, tar- 

 si, and other essential characters. These I consider distinct, well-de- 

 fined species. 2nd. Crambus chrysonuchellus and rorellus are also 

 similar in appearance, but possess distinct characters, the palpi of 

 rorellus being at least one third longer, and of different form to those 

 of chrysonuchellus. These are also well-defined species, but I have 

 seen the yellow-tinged varieties of chrysonuchellus named rorellus in 

 cabinets. 



Agrotis nigricans, fumosa, ruris, duhia, oheliscata. 



These varieties are found in most of our counties ; and I have se- 

 lected this genus, because I know many of your practical correspon- 

 spondents have taken them, and can therefore examine and judge for 

 themselves. I have taken them in woods, marshes and gardens ; and 

 we have taken several varieties in our little garden in Critchell Place, 

 from the flowers of the sun-flower, (Helianthus annuus). 



Var. 1. Anterior wings dark fuscous or blackish, with an obscure 

 black line from the base and united to the teliform stigma, and a trans- 

 verse waved line before the anterior stigma ; posterior wings ashy with 

 dusky margins. 



Var. 2. nigricans. Anterior wings dusky, with three transverse, 

 dark, waved strigae and three stigmata, all margined with black ; pos- 

 terior wings ashy with dusky margins. 



Var. .3. All the wings dark fuscous, with three stigmata margined 

 with deep black. 



Var. 4. fumosa. All the wings blackish, with the posterior stigma 

 tinged with yellow, the teliform stigma entirely wanting. 



