( Ixxxiv ) 



in the^e orpaus (as well as in others), a second student does not think worth 

 noticing; and what appears to ns to be an insignitieant distinction may 

 actnally he an accessory ciiaracter of a very important distinction so far hidden 

 from lis. Moreover, even if only (jnantitatively considered, there is no line of 

 separation between conspicuous and inconspicuous differences ; and there being 

 geograi-hica) races which are not constantly different, the differences being 

 found only iu a larger or smaller proportion of the individuals, there is also 

 uo line of separation between geographically separate jwrtions of a species 

 which are different in all individuals and geographically separate portions of 

 a species which are not dift'erent. Therefore to say which geographical 

 diflercnces are specific and which not would be entirely dependent, not on the 

 facts, but on the personal view of the iuvestigator. Spccitic 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 taxonomic 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 /lemeroj/liiiirs, rseiidox/j/i/iix, etc., upwards to Sesia, Haemorrhagia, and 

 Cephonodes, has the tenth segment (<?) 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 S/i/iiiir/h/ae scmampliorni'. Within this series we find in several 

 fenera a very j)eculiar whip-like penis-sheath (PI. LIV.), not met with anywhere 

 else. j\^i/ceri/x hypostirta with this whip will at once be recognised as a relative 

 of coj'eae, etc., and not of I'rotiwibidi/x, with which it has been associated. The 

 clasper of JS'i/r:-ri/.f is always different from that of Perigonia. The tooth of 

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

 Cocytius towards the left. The harpe of Ilerse contolvidi and the other species 

 of the genus is different from that of Aclierontla, but the harpes of both 

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

 from other characters, tliat Ilertsc anil Acherontia are near relatives. The 

 friction-jiatch of the clasper consists in Sphingidae uscmaiiopliorae of a great 

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

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

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

 a frictiou-orgau of large erect lanceolate scales which is not met with among 

 Sphingidae asemnnophorae (PL LVIII. f. 37). The ribbon of friction-scales on 

 the innerside of the eighth tergite is found only in Amhidicinae and some 

 Aclierontiiimi'. This may suffice to show that the sexual apparatus should not 

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



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



