( liv ) 



scales. A I'lirtlicr fdiitii'iiiiitioii <il' the view just c.xjji'csscd, that tlie veutral 

 scaling of the aii(enna is a relatively young character, we find in the fact that 

 there are sometimes scales on the underside of the antennae of hybrids where 

 there should not be any, tliese scales being doubtless an expression of weakened 

 vitality. We predict that by breeding in and in specimens will result which 

 show a more extended antcnnal scaling than the normal individuals. The 

 antennae of the Acj/eriidde and CastHiidae, whicli resemble in general appear- 

 ance somewhat a clubbed Sjihingid antenna, differ essentially from the latter 

 in having the greater part of the ventral surface scaled, agreeing in this respect 

 with the antennae of a great many Tineidae. Among the latter family (or 

 group of families, jjerhaps), and among the lAmacodidar, we find antennae which 

 are almost entirely covered with scales. 



Before following tlie somewhat complicated development of the sensory 

 surface, we shall shortly refer to the sense-cones and sense-bristles. The sense- 

 cones discovered by Bodine do not occur in Rliopalocera, but are widely distributed 

 in Heterocera. They are ventral, mesial, and apical in Sphingidae, one on each 

 segment, except the end-segment and the basal one or ones (PI. LX. f. 4 — 29, ec), 

 from which they are absent. The cones of the distal segments are generally 

 more prominent than those of the proximal segments. They do not always 

 stand exactly at the apical edge of the segment, being not rarely removed 

 somewhat basad (compare, for instance, Ilerse conwlmdi). However, they are 

 never absent and never abandon the mesial position . in this family. They 

 are wanting in the Castniidae, Aegeriidae, and Zygaenidae ; their absence is a 

 distinctive character not difficult to recognise. They are present on the clubbed 

 antennae of Agaristidae and Cocytia. 



The sense-bristles are stiff hairs of varying length. The Lepidoptera most 

 primitive in respect to these organs have a complete belt of such bristles on 

 each segment. Among Rhopalocera we find sncli a belt preserved in Lycaenidae 

 and Hesperiidae ; we meet with it again among the Jiigata and many Hetero- 

 cerons Frenatu. Some of tlie dorsal bristles are, however, generally reduced and 

 covered by the scaling. This is the case also in Sphingidae. The normal 

 number of the bristles found in the Hawk Moths on the non-scaled surface, if 

 we except the end-segment, is two on each side (PL LX. f. 14), one being dorso- 

 lateral, the other veutro-lateral and basal. The number is sometimes doubled ; 

 but there is never a complete transverse series, and tlie bristles are never apical, 

 the Sphingid antenna dififering therefore obviously from that of Agaristidae, 

 Zygaenidae, and many other clubbed and non-clubbed antennae. 



The dorso-lateral bristles situated close to the edge of the scaled area are 

 very often so jirolonged and become so stout that the antenna has the appearance 

 of being pectinated ; in fact, that bristle has often been mistaken for a pectina- 

 tion.* We meet with this development very commonly in tiliform and setiform 

 antennae, but never among Sphingidae. 



The ventral and lateral surface of the antenna of Heterocera, as far as 

 * Noi: Hool. iii. t. i. f. 5—11. 





