SPHING1DES. 375 



from flowers whilst the insect is on the wing. Similarly, most 

 Sphingids have a strongly developed frenulum, which Fernald 

 describes as being " attached to the basal part of the costa of the 

 hindwings, and passing through a membranous loop on the under- 

 side of the forewings ; the frenulum consisting of a single curved 

 bristle in the $ s, but of a cluster of six very short fine bristles 

 in the $ s, whilst the loop is wanting in this sex." The Amorphids, 

 however, have this organ present in a much reduced state, whilst 

 Sharp states (Insects, ii., p. 316) that, in some Sphingids, there is 

 the unusual condition of a highly-developed shoulder to the hind- 

 wing, co-existing with a perfect frenulum and retinaculum. Griffiths 

 observes (in litt.) : " The Sphingidae exhibit the highest development 

 of the frenulum, the spina of the male insect attaining its maximum 

 of size and strength, and the retinaculum being powerful and capable 

 of holding with a firm grip. In the female insect, too, the 

 spinulae are strong, and their extremities converge to a strong 

 fine point, thus forming a claw or hook, which catches the fasciculus 

 of the fore wing with considerable effect. These characters hold 

 good as regards the majority of the species of this family, but some 

 members of the subfamily Amorphinae form a noteworthy exception. 

 Of one of these, Amorpha popnli, Giorna states (Trans. Linn. Soc. Lond., 

 i., pp. 135 — 146) that it is without the appliance. Such, however, can 

 hardly be said to be the case; the male insect possesses, in the position 

 occupied by the spina in other species, a process standing out from 

 the margin of the wing, rounded in outline, and, in some few 

 examples, terminated by a minute point. This process corresponds 

 with the root or prominence which in other species carries the spina. 

 The female has a much more largely developed apparatus ; not 

 only does she possess the root process, but also a perfectly formed 

 group of spinulae, which, however, are too small to be of any practical 

 use in connecting the wings, so that the organ in both sexes may 

 be considered abortive. The retinaculum of the male is absent, 

 as we might expect, and its place is simply indicated by a most 

 inconspicuous group of scales. It will be evident on consideration 

 that the peculiar rest-position always assumed by A. populi would 

 be quite impossible in a species with fully developed spina and 

 retinaculum, inasmuch as the humeral angle of the hindwing always 

 projects before the costal margin of the forewing, and it would be 

 necessary for the moth to withdraw the bristle from- its loop every 

 time that it composed its wings for rest. A similar rudi- 

 mentary development of the part also occurs in greater or 

 less degree in several other allied species, notably in the fine 

 Australian species, Coequosa triangularis, which has the spina very 

 short and probably quite useless. Some other Amorphids, however, 

 such as the genus Mimas of Hiibner (which includes M. tiliaej and 

 Sichia (Laotho'e) quercus, have the appliance fairly well developed. So 

 also the very fine and remarkable South African species, LopJwstethus 

 du/no/ini, which is usually referred to the Amorphids, has the 

 organ well and strongly developed in both sexes. The flight of 

 many Amorphids is so different from that of the typical Sphingids, 

 and their habits are so much more sluggish, that it is interesting 

 and instructive to find a diversity in the perfection of this 

 apparatus." 



