( Ixxxii 



II, <>t 



of tin- claspi'i'. Tlif ]ir()ocssfs are cidier tiniily (■oiiiu'ctcd with tlu' slioatli 

 which they ai"e an uutgrawth or a proloiijiatioii (PI. XXX. f. 'J^!. 4s), or they 

 arc more or less movable against the sheath, the base of tlie proce.ss at the 

 juncture with the sheath being partly membranaceous, forming a kind of joint 

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

 found ill I'tTiijonia, Si:\/k, and some allies bears two sensory bristles at tlie end. 

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

 of the apical edge of tlie slieath, and is accordingly flat or concave on tlie 

 innerside (PI. XXIX. f. 9. 12); or (2) the jirocess is an ontgrowth from the 

 surl'ace of the sbeath, an enlarged tooth, and accordingly more or less conical 

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



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

 most remarkable is that of E. sagra (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 bre.iking oft" 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 'rherelra latreillei and 

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

 f« 18. 19) also break oif easily. The same obtains in centroctena rather ford i. 



Within the penis-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 aj)pliances. The duct has in most cases an 

 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 chitinised 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 Therctra 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 jienis and penis-sheath is a means 

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

 some Rodents. 



The se.xual apparatus is of great taxonomic value, and we have taken special 

 care to dissect as many species as we could. In a number of cases the apparatus 

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

 the Sphingidae can be divided according to the sexual armature into the following 

 categories : — 



(1) Species which are not diiferent from their nearest relatives in these organs. 

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



