( Ixxxix ) 



distorted, being covered on the upperside by a fold projecting backwards from 

 the snbcostal vein and ending beyond tlie apex of the cell between It' and R^ 

 Tlie width of the fold is different in the three species, being greatest in I':pistor 

 qoryon. I'mlerneath the fold—/.*;, covered by it— there is a mass of rather large, 

 short, broad, non-dentate, creamy white scales and a bnndle of woolly scale-hairs. 

 The distortion of the cell and the nenration is best visible on the nndersido of 

 the wing, where the cell bears short scaling, contrasting with the more woolly 

 scaling on the rest of the wing. In the S of Kpistor cacifer there is, besides, 

 another strnctnre on the forewing, consisting of an oblong and rather large 

 cavity on the npperside in the cell near the base. The cavity bears erect 

 scale-hairs ; the wing bnlges out on the under surface, and is here covered with 

 short and broad scabs. All three spe^iies have a very woolly abdomen in the 

 male sex, the hair-scales, which are long subdorsally, being directed obliquely 

 dorsad (except on tlie iirst tergites) and massed together in flakes. The 

 hindlegs, iiiclnsive of the tarsi, are also very woolly in these males, appearing 

 compressed and broadened. Such sexnal distinction in the legs like this occnrs 

 also elsewhere, the forelegs of Ckromis erotus, the hindlegs of Pholas aiicheiiwlus, 

 and the hindtibia of Himantoidt's uii(hita, for instance, being broadly scaled in 

 the males and simple in the females. 



The sexnal differences in the antennae have been noted above. Rhopnlo- 

 psyche is the only instance where the antennae are the same in the two sexes. 

 The palpi are on the whole smaller in the female than in the male ; the most 

 obvious differences occur in the Ambalidime. The tongue is not rarely shorter 

 in the female than in the male {J'rotambub/x, for instance). The abdominal 

 end-tufts are also very often different in the sexes, the female possessing in such 

 cases the more simplitied tnl't or nj tnl't at all (Epistor ; Sphecodina ; Cijpa ; 

 l)iloplionot(( : etc.). Tiie abdominal side-tnfts of Oxijiuiihnhjx are present only 

 in the males. The spurs of the mid- and hindtibiae and the til)iae themselves 

 are occasionally longer in the male than in the female (some Poli/ph/chus), while 

 the hindtarsus is longer in the ? than in the i of Fachi/lia Jieu.f and P//olifS 

 aiichemolus ; and the armament of the tarsi is also not always the same in the 

 sexes, the peculiar protarsal comb found in Cucytiui being a male character 

 (PI. LXIV. f. 0). The sensory hairs at the end of the fifth protarsal segment 

 (ventral side; are on the whole better develojied in the female (PI. LXIV. 

 f. 13, ,,). 



The wings, which are generally more elongate in the male, show very con- 

 spimions dimoi'jiliism in some instances : Poli/pti/ch'is puiipt'rculu and coiitraria ; 

 the species of Smeriiithnluii and Degmaptera ; Oi-ijba achemenides ; Epistor. 



More fre(pient than consjiicnous difference in shape is dichromatism. The 

 sexual dillereuce in jiattcrn and colour is often so striking that the se.xes have 

 been mistaken for distinct species. Such obvious diiferences are observed in 

 Kpintor, llim'intoidex, Oryba achernenides, Pseudosphiim, Isoymitliiirt, Erinnyis, 

 Coelo/iia J'ulcini)t<it<i, llerxe roncvlndi (not rhiynlntn), Mitumimas (instralasiae, 

 uimI other s]iecies. 



