314 THE entomologtst's record. 



because they exhibited, perhaps better than any other group, changes 

 which were now in progress. It was generally accepted by scientific 

 men that transverse bands on the wings of lepidoptera had been formed 

 by the union of transverse lines, and that many species exljibited incom- 

 plete bands, the incomplete part being formed of wavy lines. Attention 

 was drawn to the fact that the moths of these genera rested with out- 

 spread wings on rocks, tree-trunks, palings, etc. ; and that, taking into 

 consideration the probability of a more humid climate in the British 

 Isles when they were more covered with wood, there was the consequent 

 certainty of a natural darkening in colour of species with such habits ; 

 and since it might be safely assumed that the darker specimens with 

 transverse lines represented an older form, the genus Lareiitia was 

 probably one of the oldest genera in this group. As types of the changes 

 that may have occurred, MehDiippe hasiata, Melanthia ri/biginafa, 

 Melanippe vwntanata^ M. fliictuata, and Camptogramma bilineata were 

 dealt with at length. All these had, in one or other of the humid dis- 

 tricts to the north or west of the British Isles, a form with dark ground 

 colour crossed by transverse lines, the ground colour becoming whiter 

 and the transverse lines coalescing into banded form as more open, 

 drier, southern or eastern localities are reached. In the north and 

 west of Scotland, and in some parts of Ireland, the prevailing form of 

 M. fliictuata is dark grey in colour, with transverse lines, the central 

 area often being without the slightest tendency for the transverse lines 

 to assume a banded form ; but as we come south the ground colour 

 becomes paler in some localities, and at the same time the central band 

 necessarily becomes more marked, until in the south of England and 

 on many parts of the Continent, the ground colour has become white, 

 and the central band partly disappears, often forming only a small dark 

 blotch on the costa, or being entirely absent. Occasionally dark 

 specimens and completely banded forms are captured, but these must 

 be looked upon as simply reversions to the darker form. M. luontanaia, 

 taking the Hebridean and Shetlandic forms as nearest to the type, 

 shows a similar development, and the manner of suppression of the 

 central area of the band shows most clearly in a long series from various 

 localities. The special development relative to M. rubiginata was also 

 entered into ; a comparison of the Lancashire and south coast forms of 

 J/, galiata was made, and the darker ground colour and central band 

 of the northern form noted. C. bilineata has a dark ground colour and is 

 crossed by dark transverse lines in the majority of Shetland specimens ; 

 Scotch specimens also tended to be dark in many localities ; as we got 

 farther east and south there was a greater tendency for both sexes to 

 become golden, yet in many southern localities, and in some years more 

 than others, a large percentage showed reversion, by developing a dark 

 central band, more or less complete. These dark specimens in the 

 south were nearly always females, and hence this threw a side-light on 

 sexual dimorphism in this group. Mr. Tutt suggested that it was quite 

 open to assume that the paler forms were older (although he did not 

 think it possible), when the dark specimens would have to be considered 

 as instances of progressive development, instead of, as he had done, 

 looking upon the dark forms as older, and the gradual extinction of 

 transverse lines and bands, and change of ground colour, as so many 

 steps in the line of progressive development. 



