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JOURNAL OF VARIATION. 



Vol. VII. No. 12. April 15th, 1896. 



Oporabia filigrammaria, its aberrations and life-history. 



By J. A. CLARK, F.E.S. 

 With Plate. 



Having recently bred a very fine series of Oparabia tilinyatumaria 

 from eggs, obtained by INIr. Salvage from a female captured at 

 Rannoch, I thought that some account of the specimens, which are 

 very variable, would be not uninteresting to the readers of the 

 Entumolociisi' s Recunl. 



The eggs hatched from the 10th-15th of April, 1895, the larvae 

 were fed on sallow, and were full-fed about the middle of June. They 

 pupated on the surface of the ground, and the moths began to emerge 

 on August 5th, and continued to do so until November 11th, a total of 

 39 moths emerging from about 60 eggs. The larv^e are very much 

 like those of O. dilutata. 



The specimens, as will be seen from those figured in Plate iii., are 

 remarkable in having exceedingly well-developed and ample wings, 

 reminding one of O. dilutata. They also, it will be observed, present 

 a wide range of variation in both sexes. If we look upon Figs. 1 and 

 2 as representing the more usual pale silvery-grey form (ab. pallida), 

 and Figs. 3 and 4 the more extreme melanic form in both sexes (ab. 

 melana), it will be observed that Figs. 7 and 8 come somewhat inter- 

 mediate between these extreme forms (ab. intennedia). The same 

 general character is present in all, viz., a tendency for the transverse 

 lines to unite to form three or four narrow dark transverse bands on 

 the fore-wings, with an ill-defined narrow band on the hind-wings, 

 the two darker forms having a distinct tendency to extend the dark 

 tint towards the outer margin. 



Figs. 5 and 6 show a line of development directly opposed to band 

 formation, and this, I take it, represents the most ancestral form of 

 the species, having retained the parallel lines in a more or less 

 unhanded form ; and these remain, one may well suppose, very 

 similar to what was the original form of marking in all the Larentiidae. 

 From this point of view, therefore, .we may look upon this form as the 

 natural type (ab. tijpica) of the species, i.e., the centre from which the 

 other forms have radiated, some in the direction of a darker, others in 

 the direction of a lighter ground-colour, combined in both these 

 radiations with a tendency for the transverse lines to unite in banded 

 form. 



In Figs. 9 and 10 we have two extreme specimens of the fasciated 



