( Ixxxi ) 



ribbon are homologous to the undermost scales of tbe tergite, which stanil in 

 other species at the very edge of the segment, and are also here often tnrned 

 interuad. Tbe organ is as a rnle visible withont dissection, but lias as yet 

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

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

 form together one (stridulatins;) aj)]iaratus. 



Is the friction-patch a new acquisition, or have the species which are 

 withont it lost this organ ? In the Sjihiiujidae asem/mophorae the organ is 

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

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

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

 iu several generalised genera {['liolus, for instance), and its development cul- 

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

 that the ancestral Sphingid possessed a friction-])atch which consisted of 

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

 clasper, a patch perhaps similar to that of Pholm and Pseudosphinx (PI. LVIII. 

 f. 36). From this indifferent patch the two modifications arose, — in the one type 

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

 Pgilogrcnnma, Mi'ganoton, Protambuli/x, 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 Nephcle, Deile- 

 phila, Theretm, etc. In the Sphingidae semanoplwrae, 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 Sphingonaepiopsis, Proserpinus, etc. ; they are also absent 

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

 Sphingidae asemanophorae the friction-patch is comparatively less frequent. Of 

 Acherontiinae only Old AVorld 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 with 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-funnel (Fig. 3, 

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

 PI. LI. f. 17 — 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 Nijceryx, p. 414, PI. LIII. f. 44 — 48 ; compare also 

 PI. XXX. f. 33—38; PI. Llll.-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. XXV. f 2). 



From the penis-fnncel jirojects the penis-sheath, of which the former is a 

 support. The penis-sheath is jirovidcd at the end, or near it, with ])rocesses 

 and tcctli of various shapes and sizes, this armature being as diversified as that 



• Nov. Zool. V. p. 561 (lH!m). 



/ 



