( Ixxxii ] 



of the clasper. Tlie processes are either Hrmiy coiiiiect.eil with the sheath, of 

 which they are an outgrowth or a proloujiatioii (PI. XXX. f. 22. 48), or they 

 are more or less movable against the sheath, the base of the process at the 

 jnnctiire with the sheath being partly membranaceous, forming a kiiiil of joint 

 (PI. XXX. f. 31 ; PI. LIV. f. 1 — 12). The long and slender whip-like process 

 found in Prn'i/oiiia, Scxia, and some allies bears two sensory bristles at tlie end. 

 We can distinguish two kinds of processes : (1) the process is a prolongation 

 of the ai)ical edge of the slicatl!, iind is accordingly flat or concave on the 

 iunerside (PI. XXIX. f. 9. 12); or (2) the ])rocess is an outgrowth from the 

 surface of the sheath, an enlarged tooth, and accordingly more or less conical 

 and hollow, at least at the base (PI. XXIX. f. 47 ; PI. XXX. f. 38). 



Tlie processes are short or long, single or double, simple or dentate. The 

 most remarkable is that of JJ. srigra (PI. LIV. f. 13). The teeth on the 

 processes and on the sheath are small or large, single or in patches, irregularly 

 distributed or seriated, forming serrate ridges. They are in most cases solidly 

 connected with the sheath, not breaking off easily. There is, however, a second 

 kind of tooth, which is easily detached from the sheath. This tooth, which has 

 a central and three or four lateral branches, is found in Therelra latreillei and 

 allies (PI. LVIII. f. 4 — 7). The spine-like teeth of Xylophanes nechus (PI. LVII. 

 i'm 18. 19) also break off easily. The same obtains in centroctena- rutkerfordi. 



Within the jienis-sheath we find the membranaceous penis proper, the duct 

 of the sperma. This duct can be pushed out, and enters the vaginal orifice 

 with the help of the accessory ajipliances. The duct has in most cases au 

 armature of its own. It is either partly beset with small teeth (PI. XXIX. 

 f. 34. 41. 42; PI. XXX. f. 12), or the teeth are enlarged to stilettos 

 (PI. XXIX. f. 40; PI. XXX. f. 44). In other cases we find two or three 

 slightly more strongly cliitinised denticulate processes of various lengths and 

 shapes (PI. XXIX. f. 7. 8. 9. 21 ; PI. XXX. f. 16—19). Or the love-daggers 

 are strongly chitinised, acute or club-shaped (PI. LV. f. 44 ; PL LVI. f. 41). 



The armature of the penis-sheath and penis serves a double purpose. The 

 firm processes and teeth of the penis-sheath are grasping-organs like the harpe. 

 But the processes are often far too long for that purpose alone. Now, the 

 fact that the peculiar dentition of Tlierctra latreillei and allies is easily 

 detached, and the detached teeth are found in the vaginal cavity of the females, 

 makes it evident that the armature of the ])euis and penis-sheath is a means 

 to stimulate the female, analogous to the apparatus found, for instance, in 

 some Rodents. 



The se.\ual apparatus is of great ta.xonomic. value, and we have taken special 

 care to dissect as many species as we couM. In a number of cases tiie apparatus 

 is the only safe guide in the recognition of species. From tliis point of view 

 the Sphingidoe can be divided accx)rding to the sexual armature into the following 

 categories : — 



(1) Species wliich are not difierent from tlieir nearest relatives in these organs. 

 — Nephele is an example of this kind. Some Ghoerocampinae allied to gallii 



