( H ) 

 in wliicli the first is not longer or is shorter than the seeond. The segment 

 is cnrvetl, lying along the eye. The inner surface (PI. LIX. f. 20. 27 ; PI. LX. 

 f. 1) is more or less regularly annulatcd or wrinkled, flattened, or slightly 

 convex, or somewhat concave. It is naked, except the edges, with some lono' 

 hair-like scales ; or it is more or less loosely scaled for the greater part. The 

 scaling at the apex of the lirst segment (PI. LIX. and LX.) is either short, or 

 long and rough, or long and quite regular, affording in several cases conspicnous 

 characters of taxonomic value — as, for instance, iji the subfamily Clioerocampinae, 

 where the two Neotropical genera and the cosmopolitan genns Celen'o have 

 tlie scaling always rough and irregular, while all the allied Old AVorld genera 

 with the exception of Pergesa and Rkodafra, derivations from Celerio, have 

 it regular (PI. LIX. f. 19 — 2L 26. 27). A character of the greatest importance 

 in the classification of the Hawk Moths is found at the base of the first 

 segment. Tliat is a patch of variable size of short (and doubtless sensory) hairs, 

 which is always jiresent in one section of the family Qi, PI. LIX. f. 26. 27), 

 excejjt a few reduced forms, and equally constantly absent from the other 

 section (PI. LX. f. 1). The trustworthiness of the distinctive character was 

 discovered after we had separated the Acherontiinae {= Aeherontncae + Sphingicae 

 ■\- Sjihingidicae) and AmhuUcinae from the rest of the family on other grounds. 

 This basal patch was found in Butterflies and treated upon at some length 

 by Renter.* It is of wide occurrence in Moths. Its absence from Acherontiinae 

 and Amhidicinae has nothing to do with the reduction of the palpus, as it is 

 absent from the large palpi of Protoparce and other Sphingicae, while it is 

 found in the other subfamilies on the relatively small palpus of Orjjha, Berutana, 

 and other genera. The basal patch is present in Geometridae, Notodontidae, 

 Agaristidae, Nochiidac, Pijralidae, etc., etc., and assumes sometimes an obviously 

 distinctive form. ^Ve have not noticed it in Saturniidae and allied groups, nor 

 among Lasiorampidne^ Bombi/cidae, luiptcrotidm', and some other groups. How 

 far this organ can be made use of in the classification of these families more 

 complete research must show ; but we are justified in maintaining that the 

 basal patch will prove itself elsewhere an e(|ually good distinguishing character 

 as we find it to be in Spkingidai\ 



The first segment of the palpus exhibits also on the outer side characters 

 of taxonomic value. There is a kind of transverse crest near the eye in Basiothia, 

 Alcuron, and Unzela, and the apex of the segment is strongly convex externally 

 or angulate in these genera ; the crest is also found in (Jurelca and Sphingo- 

 nnejiiojtsis. A peculiar modification is found in one genus of Acherontiinae 

 {Mcgacorma) and in a great number of Choeroeampinae. It is illustrated on 

 Pis. LIX. and LX. There is at the apex of the segment, ventro-laterally, a 

 space devoid of the ordinary scaling, being either quite naked or clothed with 

 a few long hair-like but flat scales. The scaling around this naked space, 



• Ada Soc. Si: Fcnn. xxii. 1 (18',t6). — Keuter says that the basal patch of Ileterocera is never 

 elevated as in Rhopalocera. We finil that it is sometimes raised to a conspicuous ridge, for instance 

 in Pijralidae. 



