84: VARIETIES OF NOCTIL& 



into three parts, the basal area, the median area, and the outer area. 

 The first and last of these have transverse lines crossing them, the 

 second contains the stigmata, and under this, in some species, is a very 

 dark longitudinal nn-shaped mark (a modification of the claviform). 

 These may be looked upon as the great characters of the variable mem- 

 bers of the genus, the variation consisting principally of the develop- 

 ment (in some cases to a very high degree) or non-development of this 

 particular mark. Thus, in the variable species gemina, we find all the 

 different phases of variation to consist of two types : one, in which the 

 transverse lines are developed, and the species has a particularly reticu- 

 lated appearance ; the other, in which the NH-shaped mark is highly 

 developed, the transverse lines more or less suppressed, and the median 

 space more or less intensified in its upper half in colour. But just as 

 basilinea and pabulatricula exhibit single forms of a different type, and 

 gemma, on the other hand, exhibits these types blended into one with 

 intermediate forms, so we have in imauimis an almost purely dimorphic 

 species, where one form is reticulated and the other with the nn-shaped 

 mark, and yet there is no extreme development of either form, as in 

 gemina. We now come to another constant member of the group, 

 ophiogramma, with its characteristic dark costal mark, and of this 

 species I have never noticed a variety. Lastly comes didyma (oculea), 

 one of the most protean species in the whole of the NOCTU^:, and it is 

 almost impossible in this species either to classify or tabulate the 

 numerous forms, for not only have we every possible variety that can 

 be compounded of the basilinea- and pabulatricula-\.\k.Q forms, but these 

 are combined with ophiogramma-like forms with a result that defies 

 classification : we have in grey, ochreous, and red colour the trans- 

 verse lined or reticulated form ; we have in each colour the nn-marked 

 form; we have in each colour an ophiogramma-mskTked form (dark 

 costa), blended with the other forms of variation into every possible 

 intermediate form ; and, lastly, we have the unicolorous leucostigma*- 

 like forms in grey, red and black. 



Apamea, Och., basilinea, Fab. 



This species is very constant in its markings for a member of 

 such a variable genus, but the ground colour varies from a pale 

 whitish ochreous, with transverse lines and stigmata still paler, to a 

 deep, almost unicolorous, reddish brown form, some specimens being 

 of the pale or a darker ground colour, with the median area reddish, 

 the other parts of the wing being also suffused. This intermediate 

 form would appear to be the type from the description of Fabricius, 

 which is as follows : " Noctua cristata alis deflexis fuscis griseis 

 undatis, lineola baseos atra, thoracis crista bifida." " Color variat 

 ferrugineis griseisque, distincta lineola parva flexuosa atra baseos. 

 Antennae albidas " ( Mantissa,' &c., p. 183, No. 305). Guenee 

 (' Noctuelles,' vol. v., p. 206) mentions an allied species under the 

 name of finitima, which Mr. Dobre'e assures me is only a climatic 

 variety of basilinea. It would appear that this species is subject to a 

 good deal of colour variation, according to its geographical range, as 

 the Huddersfield and Hartlepool specimens are generally somewhat 

 different in ground colour to the South of England forms. 

 * Keferred in these papers to the genus Helotropha., Ld. 



