318 liEPOHTS ON THE STATE OF SCIENCE. 



several almost simultaneously. These wave Fhiyalia jnlosaria, Tephrosid 

 biuiidularia, Hybernia progeinmaria, and Diuriiea fugella. In three of 

 these, and probably in Diitrncafagella as well, the darkening was gradual, 

 but fairly rapid ; and in the case of two, and probably of all the three 

 apterous species, the females were the hrst to succumb to the darkening 

 influence. The melanism in these four species dates back probably to 

 about 1880 ; but I am less sure about Diurnea faff dla than the others, as, 

 not being so much interested in Micro-lepidoptera, I had scarcely noticed 

 this species critically for many years prior to 188G. Twenty years or so 

 before then, however, Fagella was very familiar to me as the pale grey 

 'Marcii Dagger' moth, the males of which sat in plenty on the tree 

 trunks in our woods. But in the spring of 188G, wanting a series of the 

 moth, I one evening (on April L'7) went after dark into a small wood 

 just outside the town of Hudderstield, and very soon picked off the oak 

 trunks 120 specimens, of which probably 50 were females, and out of the 

 lot two only, one of each sex, were of the pale type. Both sexes were in 

 profusion on the tree trunks, but practically all dark. Of Phujalia 

 pilosaria and Hybernia progemmaria, I fancy the females were almost all 

 black for some time prior to 188G ; but certain it is tliat they were so 

 when wc first began to notice that the males were rapidly becoming darker. 

 At first the unicolorous black males were not conunon, but thej'e were 

 plenty intermediates, and year by year the dark ones increased, and now 

 in the case of P rogemniaria in some districts largely predominate, whilst 

 in both species it is almost imjiossiblc to find one as pale as the southern 

 forms. I believe the same remarks will apply to TrpJtrosia hiundularia, 

 but as the species occurs but very rarely in uiy own inunediate district, I 

 have not had the opportunity of noticing it so closely, and so am unable to 

 say whether the females became dark before the juales. In passing I wish 

 you to note, because it will probably afiect our discussion afterwards, that 

 the apterous females of three of tb.ese species do not much affect tree trunks 

 in the daytime. The males of two of them do, and of Progemmaria a 

 very few do. An occasional female of any of them may now and again be 

 found in such situation, but probably not near 1 per cent, of what may 

 be found after dark with the aid of a lamp. 



The next species to startle us was Jluarmia ivjumdala, in 1887. In that 

 ■case Mr. George Kilner Crosland and n)yself, when working one aftei-noon 

 in a pine wood near Netherton, Huddersfield, found the species freely on 

 the pine trunks, a large proportion of the specimens evidently having 

 been black, but, having been out some time had then a somewhat 

 shabby appearance about them. From specimens boxed, however, eggs 

 were obtained which produced in 1888 a series of moths which, without any 

 exaggeration, were as black as ink, though a large number of the brood 

 were of a very dark-brown colour. Since then the black form has become 

 <iuite common in several woods in South west Yorkshire, and larv:e 

 collected indiscriminately in these woods in spring now produce, I believe, 

 a considerable preponderance of black or neatly black moths. I must 

 ■state here, however, that this form was certainly not new in 1887, for in 

 a store-box of Huddersfield-collected moths, and which I have no doubt 

 were quite fifty years old, I found some years ago two worn specimens 

 •of what undoubtedly had been black Repandata. The man who collected 

 them (now dead) had a cabinet and collection, but T believe I am right in 

 saying that all the specimens of Repandata in his series were ordinary ; 

 and whether these two dai-k ones had been considered as too bad to put 



