42 VARIETIES OP NOOTUJE 



common, although Mr. Maddison states that as many as 25 per cent, of 

 the chi he takes in Durham are var. olivacea. The form with dark 

 grey fore wings in both sexes (var. suff-usa) is most interesting, and in 

 the Bradford district, entirely replaces the type. The Linmean 

 description is : " P. Noctua spirilinguis cristata, alis deflexis canis : 

 superioribus x nigro-notatis " (' Systema Naturae,' xth., p. 514). The 

 hind wings of this species exhibit a fair amount of sexual dimorphism, 

 those of the females being darker than those of the males. In the 

 fore wings, there is a tendency in the typical form to follow the same 

 line of variation, and this, apparently, led Mr. Mansbridge in the ' Ent. 

 Kecord ' &c., vol. ii., p. 200, into supposing the females to be var. 

 sujfusa. The #-like mark varies much, and reminds one of certain 

 forms of Luperina testacea and some species of Miana and Apamea. 

 There is also considerable variation in the row of wedge-shaped spots 

 on the subterminal which, in its extreme development, forms a trans- 

 verse wavy line. The central shade is rarely well-developed, although 

 frequently distinct. The spots on the hind wings of the males (on the 

 outer margin) remind one somewhat of similarly developed spots on the 

 hind margin of the posterior wings of certain species of the Bomycid 

 genus Spilosoma. Guence says of this species : "It varies very little 

 and only in the shade of grey. Mr. Stephens has given under the 

 name of olivacea a variety which is of an olive-green colour, but I have 

 not seen it and am not certain that it really belongs to P. chi " (" Noc- 

 tuelles,' vol., vi., p. 35). Mr. C. G. Barrett writes : " At Kendal, Polio, 

 chi was to be found commonly sitting on stone walls, and in many 

 instances, so posted against ledges and inequalities, as to be fairly well 

 concealed, or, at any rate, only noticeable by those who looked for 

 them ; but on the slopes of the Pennine hills, between Oldham and 

 Huddersh'eld, where the original grey or whitish colour of the stone 

 walls has become totally changed by the constant action of smoke from 

 the cotton mills of the large towns, and the woollen mills of the 

 villages, this moth becomes so conspicuous that it may be seen h'fty 

 yards away, and is indeed more noticeable than the wall itself. Here, 

 one would suppose, would be a grand opportunity for the development 

 of the variety olivacea and other dark forms, but no such alteration has 

 taken place. I searched for hours for such varieties, and found only 

 one, although the moth actually varied much in the dark markings on 

 a white ground. One specimen I found on the blackened trunk of a 

 tree, but their preference for walls was astonishing, hardly one was to 

 be found on the isolated rocks or rocky hill sides " (' Entomologist's 

 Monthly Mag.,' vol. xxii., p. 111). The change since then must have 

 been very rapid, as the Huddersfield district now produces quite 

 melanic forms. It is quite possible that dark varieties occurred then, 

 but were too well concealed for Mr. Barrett to find them. 



a. var. olivacea, St. This beautiful variety has, when fresh and 

 in line condition, the anterior wings of a delicate greenish-grey, 

 the hind wings exhibiting the same sexual demorphism as the type. 

 The original description of Stephens is : " Viridi-olivacea, alis anticis 

 strigis 4-denticulatis albis liturisque nigris, ciliis cinereo-albis 

 olivaceo maculatis, posticis fuscis, striga pallida." " Olive-green, ant. 

 wings with 4 denticulated white strigse, the first abbreviated at the 

 base ; the second, before the middle, angulated towards the costa ; the 



