t3Y R. J. TiLLYAftD. 30<) 



frenulum is of the usual type, i.e., elongated, and with all the 

 bristles fused together into a single, strong bristle. In the 

 female, there are two long and delicate l^ristles (as in Pln^ia) 

 accompanied usually by several sliorter bristles at their base. 

 The retinaculum of the female is (jf the usual type, consisting of 

 a patch of forwardly projecting scales, developed on the under- 

 side of the cubitus of the forewing; but this retinaculum is situ- 

 ated so far from the wing-base, that only the two longer bristles 

 can become engaged in it, and tlie connection appears to be easily 

 lost during Hight In the male, this retinaculum of scales upon 

 the cubitus is refautrd ([ii'ifr cott.spicxoftslt/ {Text-^'^AG, rt'), to- 

 gether with an additional development of a di(/ht ovrr/o/diur/ of 

 the edge of the radius in a backward direction {rl). Usually, 

 during Hight, the frenulum of the male is caught in the curve of 

 this overfold, as sliown in the figure. But if, at any tijne, the 

 frenulum slips out of this somewhat precarious hold, it is then 

 caught up by the still existing retinaculum on the cubitus, and 

 the insect can continue its Hight in the manner of the female. 



Thus we see that, in St/tientoii, the type of coupling-apparatus 

 for the wings is much closer, in the two sexes, than it is in other 

 frenate moths; and we can scarcely doubt that the condition in 

 tlie male of this genus is that which preceded, in the males of 

 other frenate moths, the more specialised condition that we tind 

 in them at present. 



If now, we turn to the genus Enschemon^ which is claimed by 

 some authors as a moth, by others as a buttertly, we Hnd that 

 the male has a well-developed frenulum and retinaculum of the 

 type found in other frenate moths, i.f., more highly specialised 

 than in Syufinon. But, on examining the female, I was surprised 

 to find no trace whatever of a frenulum or retinaculum; and it 

 it is evident that this sex couples its wings in the amplexiform 

 maimer of the Butterflies, by means of its large humeral lobe. 

 Thus, judged only on the form of its wing-coupling apparatus, 

 the male of Euscheinon is a frenate moth, the female a butterfly. 

 This genus, then, exactly bridges the gap between the old sub- 

 divisions Heterocera and Khopalocera. That this is not a mere 



