152 



THE ENTOMOLOGIST. 



Melanism is, as is well known, of very wide occurrence in 

 our fauna, but I think that even it can only be regarded as 

 really characteristic of a comparatively limited number of groups. 

 Confining our attention, for instance, to the Geometrides, we 

 only find it at work to any large extent in two of the principal 

 families, the Boarmiidse (sens, lat.) and the Larentiidfe, although 

 I admit that they are the two largest numerically; but even in 

 the former of these the distribution of melanism seems somewhat 

 partial and irregular. Thus the "thorns" (Ennominse), although 

 occasional dark aberrations of Ennomos quercinaria, &c., show 

 that they are capable at least of " melanochroism," cannot be 

 said to markedly favour variation in this direction ; whereas the 

 Boarmiinae (the genera Boarmia, Tephrosia, &c.) show few 

 British species indeed which are free from the tendency. The 

 other principal geometrid families— the Acidaliidae or "Waves," 

 the Geometridae or " Emeralds," the Orthostixidae, (Enochromi- 

 dse, Cyllopodidffi, &c., of which we in England know so little — 

 are practically a "negligeable quantity" when we are considering 

 melanism ; I am not forgetting a few isolated cases, such as a 

 fine melanochroic specimen of Acidalia aversata bred by my friend 

 Mr. W. G. Sheldon, but (with all deference to the Evolution Com- 

 mittee of the Royal Society) I cannot allow that the Linnean 

 (banded) type of this species has any right to be included in 

 the series of melanic forms. As to the absence of prominent 

 melanism in the tropical families, &c., I can only say that, so 

 far as is at present known, it seems to be mainly a phenomenon 

 of the fauna of the holarctic region. 



In the Larentiidae melanism is decidedly conspicuous. Several 

 species of Eujyithecia, &c., have very interesting black or blackish 

 forms— e.g. Chloroclystis rectangulata (ab. nigrosericeata, Haw.), 

 Eupithecia albipunctata (ab. angelicata, Barr.), E. virgaureata 

 (? var. altenaria, Stgr., pro parte), E. vulgata (ab. siihfuscata, 

 Haw.), E. denotata = campanulata (? var. atraria, H.-S.), &c. 

 The Shetland form of E. venosata {YSiY.fumosa, Gtvegs. = nuhi- 

 lata, Bhtsch.*) is likewise well on the ro^d towards melanism, 

 compared with the pale typical form of the species. In Larentia 

 (in sens. Guen.) we get L. multistrigaria (ab. mihilata, Tutt), 

 L. ccesiata (ab. glaciata, Germ.), L. fiavicinctata (Staudinger has 

 recently named our dark Scotch race var. ohscurata), and even 

 L. didijmata (ab. nigra, mihi, n. ab. — Barrett, Lep. Brit. viii. 

 176, pi. 346, fig. 2c). In Hydriomena (Ypsipetes), nothing could 

 be much more extreme than some of the forms of II. furcata 

 (sordidata). In Thera, T. variata var. ohliterata, B. White 



'■''' I cannot trace the original reference to Gregson's overlooked varietal 

 nanae, but it is certainly long prior to that of Bohatsch, for it appears in 

 Eobson & Gardner's list, 1886; probably it was a manuscript name before 

 that date. I have to confess that I had also lost sight of Gregson's name for 

 the Orkney var. of the same species — var. ochracce, Gregs. (Young Nat. vii. 

 128) — and renamed it orcadensis (Ent. Rec. xiii. 33C). 



