OPORABIA AUTUMNATA. 55 



notwithstanding their great structural differences. There is also 

 a third form, which may be termed a '* sub-species," which 

 deserves to be kept carefully distinct from the others by the 

 systematist, though not differing structurally from No. 2. I will 

 return to this third form when I have differentiated the two 

 indisputably valid species : — 



No. 1. — Dilutata, Bork. No. 2. — Aiitumnata, Bork. 



Ova. — Highly polished, hardly Much less poHshed, deeply 



perceptibly pitted. pitted. 



Larva. — Never with couspicu- With conspicuous yellow longi- 



ous longitudinal yellow striping. tudinal lines, though often becom- 



Very generally with brown or ing indistinct in a(/(i/i larva. Never 



reddish blotches. with brown or reddish blotches. 



Imago. — Male genitalia with a Male genitalia with no hook 



hook on the harpes. Male antennae on the harpes. Male antennae 



decidedly thickened. slender. 



Ground colour always with a Ground colour clean white or 



dirty ochreous or brownish tinge, grey, or even blackish, or with a 



violet tinge, never ochreous-tinted. 



Fore wings not very glossy. Fore wings very glossy. 



"Elbowed line" rarely angu- " Elbowed line " nearly always 



lated near the costa. angulated near the costa. 



I have omitted in this tabulation a large number of less 

 important points, which are nevertheless very interesting to the 

 close student of these species. 



The third principal form is our moorland filigrammaria, and 

 though this is such a specialized race that nearly all entomo- 

 logists can easily distinguish it from both Nos. 1 and 2 of the 

 above, even while failing to distinguish No. 2 from No. 1, yet 

 when we come to an analysis of the differential characters we 

 find that it agrees almost precisely with those given for aiitumnata 

 in the tabulation, and those entomologists who are averse to 

 multiplying species may like to sink it as " autumnata vox. fili- 

 grammaria." To treat filigrammaria as the type and autumnata 

 as the variety, as Doubleday ultimately did, is absolutely inde- 

 fensible on any and every ground ; from the bibliographer's 

 point of view, aiitumnata, Bkh., is long prior to filigrammaria, 

 H.-S. ; while the student of distribution will lay more emphasis 

 on the fact that, whereas autumnata is widely distributed through 

 a great part of the palaearctic region, filigrammaria seems to be 

 restricted to a few limited moorland and mountain localities in 

 certain parts of the British Isles. 



The chief differences between autumnata and filigrammaria 

 are the smaller size of the latter, its differently shaped female 

 (the fore wings more cut off at the anal angle), its generally 

 browner tone (hardly ever with really white forms) and its usually 

 sharper markings, particularly the somewhat better defined sub- 



G 2 



