( Ixxxi ) 



ribbon are homologous to the nmlermost scales of the teryite, which stand in 

 other species at the ver}' edge of tlie segment, and are also here often turned 

 internad. The organ is as a rule visible witiiont dissection, bnt has as yet 

 escaped observation, as lias also the friction-patch of the clasper. There can 

 be no doubt that tiie ribbon of the eighth tergite and the patch on the clasper 

 form together one (stridulatin":) ajiparatns. 



Is the friction-patch a now acfjnisition, or have tlio six'cies which are 

 withont it lost this organ ? In the Spliinyidae asi'm'iiwpliorae the organ is 

 found in the more generalised forms and never in the strongly specialised 

 (reduced) species. In the Sphingidae semanophorae the organ is absent from 

 many of the most specialised genera ; it consists of a multitude of small scales 

 ill several generalised genera (P/iolus, for instance), and its development cul- 

 minates in some Ilippotion with one large scale. From these facts we conclude 

 that the ancestral Sphingid possessed a friction-patch wliich consisted of 

 numerons small scales not very different from the ordinary scaling of the 

 clasper, a patch perhaps similar to that of Pl/olus and Pseuclosphinx (PI. LVIII. 

 f 30). From tliis indifferent patch the two modifications arose, — in the one type 

 the scales remaining numerons and becoming closely packed together, as in 

 Piiilogromma, Meganoton, Protambuli/.r, etc. ; in the second type the central 

 scales becoming enlarged and seriated, and assuming a half-erect position, with 

 the broad sides turned more or less dorsad and ventrad, as in Ncphele, Deile- 

 pJdla, Tlieretra, etc. In the Sphingidae sfinanophorne, where retrogressive 

 development is comparatively rare, the friction-scales are found in the greater 

 number of species. They are lost in the reduced or otherwise strongly 

 specialised forms like Sj/hingonaepiopsis, Proserpinus, etc. ; tiicy are also absent 

 from modified claspers like those of Ilaemorykagia, Perigonia, etc. Among the 

 HpJdngidae asemariophorae the friction-patch is comparatively less frequent. Of 

 Arherontiinae only Old World genera have preserved it, not one of the 

 numerous American species possessing the organ, while a large proportion of 

 Old and New World Ambulicinae. are provided witii it. 



The area between the two claspers and the tenth sternite is more or less 

 membranaceous. There is a central hole, of which the edges are more or less 

 raised and chitinised, forming what we have termed* a penis-fnnnel (Fig. 3, 

 P-F). This penis-funnel {P-F, PI. XXIX. f. 38. 39. 47 ; PI. XXX. f. 41 ; 

 PI. LI. f. IT — 25) is vestigial or distinct; it has often a special shape, and has 

 an armature of its own which is of great help in the discrimination of species 

 in more than one case (see Ni/n'ri/x, p. 414, PI. LIII. f. 44 — 48 ; compare also 

 Pi. XXX. f. 33—38; PI. LIII. f. 13. 14). Above the penis-funnel there is in 

 a few cases a further armature consisting of a pair of processes, one on each 

 side («, PI. XX^'. f L'). 



From the penis-fnuKsl projects the penis-sheath, of which the former is a 

 snjiport. The penis-sheath is provided at the end, or near it, with processes 

 and teeth of various sliapes and sizes, this armature being as diversified as that 



* Xov. Zool. V. p. 561 (1S08). 



/ 



