39 



line was due to the union of a row of dots with thickenings 

 of the sHght curves of that line. He referred to the habit of 

 the species of hiding under leaves, &c., on the ground, and 

 thought that no protective resemblance was necessary. The 

 darkening might be connected with a humid climate, and 

 instanced Tephrosia biundularia as being dark in some moist 

 localities. Mr. Tutt remarked that the development of the 

 strongly scalloped line had been worked out by the Rev. Mr. 

 Burrows in another species, namely, Calaniia lutosa ; the 

 feature was common to many of the genera of the Noctuina, 

 and was well developed in some of the TriphcBna alliances. 

 He further said that where the melanic form occurred locally 

 in Aberdeenshire, Moray, Sutherland, the Orkneys, and the 

 Isle of Lewis, the climate was notoriously mild, Moray being 

 one of the mildest districts in Scotland, and that therefore 

 low temperature could not be the influence causing the dark 

 forms. He considered, without going into the initial cause 

 of the variation in the organism, that the dark colour was 

 due to natural selection, which had developed the melanic 

 tendencies for protective purposes. In his experience T. 

 orhona {comes) settled on the bare ground on the sand-hills 

 at Deal. With regard to the synonymy of the species, he 

 considered that the old nomenclature was the correct one, 

 and that T. orhona, Hufn., should be the name used for this, 

 the commoner of the two species, and T. subsequa, Hb., for the 

 rarer; Hufnagel's description containing no mention of the 

 short oblique dark costal mark that characterised T. subsequa. 

 Mr. McArthur said that in Orkney, where the only form of 

 the species found was the dark one, he met with very few 

 examples where high furze existed, the majority of them 

 being taken on an almost bare peat moor, where they availed 

 themselves of whatever cover they could find, and he had 

 never seen one at rest fully exposed on the peat. Mr. 

 Adkin, in reply, thought that possibly the flouncing of the 

 second line, noticed in the examples from Scilly, was a case 

 of atavism ; but he could not accept this as an explanation 

 of the curtisii forms, regarding which he considered our 

 present knowledge was too incomplete to admit of any 

 definite conclusion being formed. As to nomenclature, he 

 noticed the name used for the commoner of the two species 

 in the most recent standard works was T. comes, Hb., and 

 he had no reason for supposing that their authors had not 

 been able to form a sound judgment on the question. 



