32 



THE ENTOBIOLOGIST S RECORD. 



A. populi, would pro parte be identical with the above aberration ; yet, 

 my nomination is more comprehensive, as I have included in it all 

 the lighter-grey or ash-grey coloured specimens the outer area of which 

 appears often olive-coloured, bronze-brown or rust-brown, the markings 

 of which generally are more or less obsolete, and the rust-coloured 

 basal spot of which is usually of a weaker colovir. Therefore I have 

 not restored the name ab. borkhansejii in my variation scheme, because 

 this name only fits an aberration of an absolute greenish-grey colour. 

 One does not require an extension of ab. treiiudae, Borkh., which also 

 appears in the cinerea group, because it is without any markings, and 

 because all areas seem of the same light -grey colour. 



The identification of ab. borkhauseni, Bart., eind oi ah. pallida, Tutt, 

 made bj'Dr. Speiser, and already referred to, is therefore not accurate. The 

 aberration oi A. populi, described 1853-4 by Dr. Glaser as var. tremulae is, 

 indeed, identical with ab. pallida, Tutt, but Glaser's aberration is, as 

 mentioned already, neither ab. trem idae, Borkh., nor ab. borkhameni, Bart. 

 I do not agree with Mr. Tutt's suggestion (Brit. Lep., vol. iv., p. 473) 

 that Glaser probably intended to include in his ab. tremulae all the pale 

 obsoletely-marked aberrations of this species known to him, although 

 he does not say so. If Glaser has not said it, he surely did not mean it. 

 I maintain my opinion, published in 1903, that Glaser, in diagnosing his 

 var. tremulae, has shown himself unreliable. (6'/'. the preceding footnote.) 

 Glaser probably changed his diagnosis, through having seen, in 1856, the 

 newly-published figure of var. tremulae by Koch. It would appear that 

 Glaser, thinking that the description of his var. tremidae (1853-4) did 

 not very well agree with Koch's picture, changed his diagnosis, 

 considering no longer the " white-grey moth mixed with a weak rust- 

 yellow colour" as var. tremHlae,hut the one with "greenish-white colour, 

 weaker markings and more or less obsolete rusty-coloured basal spot." 

 I think that hereby this remarkable alteration of his diagnosis is to 

 be explained. 



In his above-mentioned work, Koch evidently thought it necessary 

 to make sure of ab. tremulae, Borkh., as it seems that he did not 

 think Glaser's description in 1853-1854 either sufficient or accurate. 

 Anyhow it is remarkable that he, against his usual habit, does not 

 refer to Glaser this time. He only mentions Glaser as mixing Bork- 

 hausen's tremulae with the Russian tremidae, F.d.W. It must be 

 remembered that, owmg to the critical remarks published by Herr von 

 Heyden and Koch {Stett. ent. Zeitij., 1855, p. 41, p. 113 and p. 294; 

 1860, p. 301 ; 1861, p. 57 and p. 225), the latter Avas boycotted at that 

 time in Frankfurt-a.-M. As the figure of Esper was a failure, Koch 

 painted from nature a specimen exactly corresponding with Bork- 

 hausen's description, remarking on p. 475, that the original shows even 

 less shading than the figure and is quite of a light-grey colour. Yet, his 

 picture again is of quite a different colour. Perhaps, at the base of 

 the forewings the light-grey colour predominates, and is to be seen in 

 the greater part of the median area, and as a light band in the outer 

 area ; but the ground-colour is rather light grey-brown, in which the 

 nervures of the forewings, as also the margin, appear brown ; the 

 nervures of the hindwings are of a reddish-brown colour, whilst the 

 base of the latter appears weak rusty-red. The thorax is lighter than 

 the abdomen, which has brown segmental incisions, the antennae are 

 uncoloured. [To be concluded.) 



