( Ixxxiv ) 



ill these (irgans (us well as in (itiiers), a K'coml student, ddcs not think worth 

 noticing-; and wliat appears to ns to he an insigniticant distinction may 

 actually lie an aecessory character of a very important distinction so far bidden 

 from us. Moreover, even if only quantitatively considered, there is no line of 

 separation Ix'tween conspicuous and inconspicuous differences ; and there being 

 geograjiliiciil races whicli are not constantly different, the differences being 

 found only in a larger or smaller jiroportion of the individuals, tliere is also 

 no line of sejiaration between geographically separate portions of a species 

 which are different in all individuals and geographically separate portions of 

 a species wliich are not different. Tiierefore to say which geographical 

 differences are sjiecific and which not wouhl be entirely dependent, not on tlio 

 facts, but on the personal view of the investigator. Specific distinctness, however, 

 as we conceive it, is a phenomenon in Nature independent of the student, and 

 therefore independent of all individual opinion. A view of specific distinctness 

 making it dependent on personal opinion must, therefore, necessarily be erroneous. 

 The taxonoraic value of the sexual armature is not confined to subspecies 

 and species. In many cases there are peculiarities in these structures which 

 relate to all the species of a genus, and only to these. Or a group of genera 

 possesses in some or in all members a certain structure not found elsewhere. 

 In fact, the genital organs are very often of great help in locating a genus 

 or a species correctly. We will give some illustrations. The series of genera 

 from Hemeiojilanes, Pseudofjjhinx, etc., upwards to Sesia, Huemorrhagia, and 

 Cephonodes, has the tenth segment (c?) of the same type ; we find here only 

 modifications of one type of anal segment, which do not recur among all the 

 rest of the Spkingidae semanophorae. Within this series we find in several 

 genera a very peculiar whip-like penis-sheath (PI. LIV.), not met with anywhere 

 else. Ni/ceri/x hypostieta with this whij) will at once be recognised as a relative 

 of coffeae, etc., and not of Protambulyx, with which it has been associated. The 

 clasper of Nyceri/x is always different from that of Perigonia. The tooth of 

 the penis-sheath of Protoparce is always directed towards the riglit side, of 

 Cocytius towards the left. The harpe of llerse convolviili and the other species 

 of the genus is different from that of Acherontia, but the harpes of botli 

 genera are built up after the same type, confirming the conclusion arrived at 

 from other characters, that Ilerse and Acherontia are near relatives. The 

 friction-patch of the clasper consists in Spkingidae a semanophorae of a great 

 number of mostly small scales lying more or less flat on the clasper; such 

 patches as represented by PI. LVIII. f. 29 — 34 do not occur in the Spkingidae 

 semanophorae. On the other hand, this section possesses in many members 

 a friction-organ of large erect lanceolate scales which is not met with among 

 Spkingidae asemanopkorae (PI. LVIII. f. 37). The ribbon of friction-scales on 

 the inuerside of the eighth tergite is found only in Amhtilicinae and some 

 Acker ontiinae. This may suffice to show tiiat the sexual apparatus should not 

 be studied merely with the view of finding differences between species. 



The general results arrived at with respect to the male sexual armature 



