( Ixxxiii ) 



and tyijihorhiiii' ulsu do not .show any apparent ditt'erenccs. Protoparce jlorestan 

 and Ch laciio(/ nrmma jasniinearum, thougli genprically distinct, have the same sexual 

 anuatnre. Tiiis kind of identity shonld not be contonuded with similarity arising 

 out of reduction. It happens that members of ditferent subfamilies become similar 

 in one or the other organ in consequence of the loss of special structures. Such 

 species are, however, never the same in all parts of tlie copulatory apparatus, as 

 is the case in the insects mentioned lu'fore, the list of wliich is by no means 

 exliaustod l)y tlie few species used as illustrations to show that it is (juito erroneous 

 to maintain tliat all specifically distinct Lejiidoptera exhibit diti'erences in the 

 copulatory organs. 



(~) Species which are difi'erent from the nearest relatives, but do not show 

 any marked geographical variatiou in the sexual armature. — Here belongs by 

 far the greater proiiortion of the Hawk Moths. The specific differences are very 

 slight or very conspicuous, or intermediate iu degree. They may lie found in one 

 single organ, or in more, or iu all. The differences may be sliglit in some 

 species, and great iu others of the same genus. Two species may difi'er strongly 

 in external features, and little in the sexual armature, or the reverse may be the 

 case. There is every conceivable gradation in this respect. There is always 

 some individual variation, as a matter of course. AVhen examining the 

 armature of only one individual, one is sometimes induced to cousider a certain 

 outline or structure as specific, while it is in fact only an individual character; 

 if possible, a number of specimens from different localities should be examined. 

 Individual variation is most obvious in species with complex structures, but it 

 is here far less easily misleading than in the case of simple structures, because 

 the s])ecific differences are as a rule more conspicuous there than here. 



(3) Species which differ in the copulatory orgau from the allies and vary 

 in themselves geographically. — Geographical variation is most often met with 

 and is most conspicuous in those forms which are sedentary iu habits. Sluggish 

 species with functionless mouth-])arts and reduced power of flight, species of 

 which the sole function as imagines is ])ropagation, are especially liable to 

 develop into geographical races with differences in the sexual armature. The 

 phenomenon occurs often among Ambidicinae. The geographical differences in 

 these organs, which may or may not be accompanied by differences in external 

 features, are t)Ccasionally surprisingly great. In Pseudoclanis postica from 

 \Vest and East Africa (PI. XXXII. f. 1:2. 13), and Poli/jAj/chus trilineatus'Jrom 

 Ceylon, North India, and the Philippines (PI. XXV. f. 2; PI. XXXIV. f. 7—10), 

 we have extreme cases of geographical variation in the copulatory organs, 

 which cases are the more instructive as the races exhiliit only slight external 

 differences. Oxf/ambuli/x substriiiilis (PI. XXX. f. 3. 4. 5) is also an example 

 to the point. It is quite erroneous to say that differences in the sexual armature 

 are always of specific value. Geographical races may be difi'erent or not in 

 these organs ; aud the diflerence may be minute or consjiicuous. It is idle to 

 maintain that geographical representatives are sjiecifically distinct, if the sexual 

 armature shows obvious differences. What one investigator considers obvious 



