44 BRITISH LEPIDOPTERA. 



of this sex is accordingly great, and its slow and steady habit 

 of flight is very different from the rapid, zigzagging flight of the 

 males. The male antenna is described by Chapman as follows : 

 Length, 8mm. in a small specimen, 12mm. in a large one, joints bearing 

 pectinations, 58 in one antenna 11mm. long, 69 in another 8mm. long, 

 and 78 in one 12mm. long. The first joint of the antenna is very large, 

 07mm. wide, o'4mm. long, or 07mm. if the cylindrical process (•35mm. 

 wide) that projects into the cranial socket to form the articulation be 

 included. This joint is rounded, globular if its unequal diameters allow 

 that word to be used. It is clothed with long hair-scales. The 

 next joint (second) is larger and squarer than those that follow, but 

 is rounded on its basal aspect towards first joint, and swells out 

 somewhat (urceolate) towards third joint, it also has strong brushes 

 of hair-scales. The third joint is a little wider than the fourth and 

 carries a mere rudiment of a plumule. On the fourth joint, the plumule 

 is as long as the width of the joint (about ^mm.). The pectinations 

 reach full length about the 25th joint, and diminish again about twenty 

 to twenty-five joints from the end, at this point the shaft of the 

 antenna has dwindled to about half its thickness at the base. The 

 shaft is circular in section, the dorsal J occupied by scaling irregularly 

 disposed, so that no definite rows can be made out. The scales are 

 narrow and bifid, the two points rounded and blunt. The ventral £ is 

 occupied by the origins of the pectinations ; joints somewhat 

 oblique. The pectinations (plumules) are about i'4mm. long, the 

 hairs on the inner surface are arranged in rows transversely to the 

 axis of the plumule. Each row begins at the middle line of the ventral 

 aspect of the plumule and passes outwards. The rows on each side 

 of the middle line may be opposite to or alternate with each other 

 on different parts of the same plumule, but the alternate arrangement 

 seems the normal one ; an actual middle line is almost free of hairs 

 but may have some single scattered hairs. Each row may contain 

 8 to 10 hairs, one of the largest plumules has on either side about 

 53 rows. The individual hairs are about •037mm. in length. 

 Supposing half the plumules are big enough to have only half the 

 number of hairs of the longest, then the total hairs on an antenna 

 would be about 70 X2a2X 53X10-^1^ = very nearly 100,000. The 

 end of the plumule is perceptibly but not markedly swollen or 

 clubbed. The hairs on this portion are rather shorter and thicker 

 than on the shaft, more like small spines, they rather escape from 

 their regular alignment, are not perhaps quite so numerous and 

 invade a little the lateral (or almost outer) area of the plumule. The 

 proximal side of the club is rounded off and the distal a little 

 produced, and, quite at the side of the extremity, but what may be 

 really the true end curved round, carries the strong spine, so that 

 this lies parallel with the shaft of the antenna and points in the 

 same direction. It is rather longer than the thickness of the shaft 

 of a plumule ('055111111.) about 'o6-'07mm. Its width at base is 

 about one-fifth of its length, and at three-fifths of its length it has a 

 notch as if for a hair base. Just beyond this is a strong bristle, 

 about half the length of the spine. The other hairs in the neigh- 

 bourhood belong rather to the regular scries of hairs. The 2 

 antenna is of approximately the same length, and has the same 

 number of joints as that of the J . The form of the basal 



