( Iv ) 



it is not scaled, is covered with liliac, only tiie parts near the joints and 

 close to the dorsal scaling being in many cases naked or sparsely ciliated. 

 Pagenstecher * calls the antennae of Cullklalidae "naked," and Hampsont 

 describes those of Aijuriatidae as being " not ciliated." Both anthors are 

 wrong, the antennae of Calluhdidae and of Agnrisfidue being scaled above 

 and ciliated below. There is no antenna among Lepidojjtera which is not 

 ciliateil, and the term "naked" can with some jnstitication only be emjiloyed 

 for antennae which are not scaled, and therefore have a naked dorsal surface 

 (apart from some bristles and setiferons jiits). The evenly ciliated ventral surface 

 as we find it in Rho])alocera among the Lijcaenidae and Jlfxperiidae, and in 

 great abnudance among the Heterocera, more esj>ecially in the female se.x, far 

 less often in the male se.v, represents a generalised state of development from 

 which a variety of specialisations have started, which, though resulting in 

 widely different structnres. have nevertheless all the same tendency— namely, 

 to make the antenna more efficient as an organ of sense. This is accomplished 

 by enlargement of the area bearing the sensory organs— ?'.<;. by the increase in 

 their number— or by concentration of the organs, or by enlargement of the 

 organs themselves, these modifications obtaining either singly or together. The 

 concentration of the ciliated area into such well-circumscribed grooves as are 

 described and figured in Nov. Zool. vi. p. 374. t. 14. 15, does not occur amono- 

 the Heterocera. The enlargement of the distal part of the antenna into a 

 club, which is normal for Rhopalocera, among which non-clubbed antennae are 

 extremely rare (Pseiidopontia), is met with in a number of Heterocerons families, 

 such as Castniidae, Aegeriidae, Sphingidae, Zijgaenidae, Agaristidae, CalUda- 

 lidae, and also among Gcometridae and Noctuidae. As regards mere outline 

 the clubbed antennae of representatives of different families are sometimes not 

 distinguishable. The Australian Castniidae, which appear to form a different 

 subfamily from the Neotropical species of that family, resemble in the short 

 and abrupt club certain I'ieridae, and some Henperiidae and Neotropical 

 Castniidae have practically the same antennal outline as some Sphingidae. The 

 most strongly clubbed antenna of Sphingidae we find in Haemorrhagia and 

 Rhopalopsyche ; from these to the setiform antenna of Megacorma there occur 

 all intergradations in shape. It is by no means only the ciliated surface which 

 becomes expanded in the clubbed antennae of Sphingidae. The dorsal area is 

 often proportionally more enlarged than the ventral area. This can best be seen 

 in a frontal view of a segment of the club of Cephonodes or Haemorrhagia, 

 where the axis of the club will be found further ventral than in a segment 

 from the middle of the antenna. By axis we mean an imaginary hollow 

 cylinder of the width of the jiiints.J There is no real axis, each segment 

 representing, so to sjieak, a box with an oi)ening each at the proximal and 

 distal sides. The edge of this opening is more or less raised and joined to the 

 edge of the ojiening of the next segment. The diameter of the cavity of the 



• TierrcH, xvii. (ir02). f Lejnd. Plialanme iii. p. 51.i (1901). 



} Joint and segment should not be confounded, 



