( 396 ) 



external groove is left uncovered; such joints (f. 55) appear to be one-grooved, but 

 show the carinae very well, and the vestige of the second groove becomes visible on 

 removing the scaling. 



Very different from the two-grooved antennae of Papilionidae and Xijmphalidae 

 are the antennae of Erycinidne aud Pkridae. In the Krijcinidae the joints have in 

 many species a slight mesial depression, which in other forms has developed to a 

 rather deep groove, sometimes extending from the base to the ajiex of the joint 

 (f. 11) ; the proximal joints of the stalk never have such grooves iu this family. 

 This simple median groove is found again in all Pierinae; the groove varies very 

 much in form and size — in NathaUs it occupies the whole ventral surface of the 

 joint— but is always regular in shape. The lUxmorjildinae have three grooves 

 instead of one, all three standing at the apex of the jouat ; one is mesial and larger 

 than the others, which are lateral ; in many cases the three grooves are not entirely 

 separated from each other (figs. 29 — 31). 



The Heterocera have very often the simjjly cylindrical antennal joints found in 

 Eesperiidae, Lycaenidae, and some Papilionidae ; but one-, two-, or three-grooved 

 antennae like those of Papilionidae-Nymphalidae, and Enjcinidae-Pieridae, do 

 not occur. It is true that many not-pectinated antennae have the joints laterally 

 impressed {Agaiiaidae, Nov. ZooL. 1896. t. 4. f 10), but tliese impressions extend 

 ventro-dorsally and cannot be compared with those of Papilionidae-Nymphalidae. 

 The grooves aud oariuae are a .special feature found only among Butterflies. 



e. Sense-Bristles. — It now remains to give a brief survey of the stages of 

 development of that antennal sense-organ which I described above as sense-bristle. 

 In opposition to the fine sense-hairs, the sense-bristles are not confined to the not- 

 scaled area of the joints, but occur also on the scaled portion of the antenna. I have 

 not paid special attention to the bristles that stand on the scaled dorsal side of the 

 antennae, firstly, because their study would require denudation of the joints, and 

 secondly, because their number and arrangement is so irregular in the species 

 examined more closely that 1 did not find any facts of greater weight for classifica- 

 tion. The bristles on the not-scaled area of the antennae are mostly easily observed, 

 but sometimes they are so short that it requires a higher magnifying power to 

 discern them from the fine sense-hairs. The number aud especially the arrangement 

 of the bristles offer in many instances very striking distinguishing characters. 

 Those species of Lycaenidae in which the distal joints are covered with tine sense- 

 hairs dorsaUy and ventrally have also the sense-bristles evenly developed on the 

 dorsal and ventral surface, each not-scaled joint bearing a complete belt of bristles 

 (f. 9). In all other Butterflies the dorsal aud ventral side of the joints are different 

 in the devel()i>ment of the bristles, but we find in some Erycinidae a series of bristles 

 nearly all round the distal joints. The joints of the stalk have often the bristles 

 less regularly arranged than the joints of the club. The not-scaled ventral surface of 

 the club bears in all Lycaenids and Hcsjierids a transverse series of bristles (often 

 reduced in number), and such a row of bristles we find also in certain Papilionidae, 

 but here tlie series is irregular (f. 39, Leptocircus). The transverse, apical, series of 

 certain Erycinidae is reduced in other forms of this family, sometimes so mnch, at 

 least on the stalk, that only one, externo-lateral, bristle is left (f. 14) ; the lateral 

 bristles are nearly always develo])ed and stand generally near the middle of the 

 joint, while the more mesial bristles keep their position near the apical edge. 

 The bristles of the Pieridae are constantly reduced in number ; most species have a 

 lateral, median or submediaii, pair, and an ajiical, submesial, pair (figs. 15—31). 



