348 
SEXUAL SELECTION. 
Part II. 
with these species, and the males require great strength 
and size in order to carry the females through the air. 
Increased size has here been acquired in opposition to 
the usual relation between size and the period of de- 
velopment, for the males, though larger, emerge before 
the smaller females. 
We will now review the several Orders, selecting such 
facts as more particularly concern us. The Lepidoptera 
(Butterflies and Moths) will be retained for a separate 
chapter. 
Order, Thysanura . — The members of this Order are 
lowly organised for their class. They are wingless, 
dull-coloured, minute insects, with ugly, almost mis- 
shapen heads and bodies. The sexes do not differ ; but 
they offer one interesting fact, by shewing that the males 
pay sedulous court to their females even low down in the 
animal scale. Sir J. Lubbock 17 in describing the Smyn - 
ihurus luteus , says : “ it is very amusing to see these 
“ little creatures coquetting together. The male, which 
“ is much smaller than the female, runs round her, and 
“ they butt one another, standing face to face, and 
“ moving backward and forward like two playful lambs. 
“ Then the female pretends to run away and the male 
“ runs after her with a queer appearance of anger, gets 
“ in front and stands facing her again ; then she turns 
“ coyly round, but he, quicker and more active, scuttles 
“ round too, and seems to whip her with his antennae ; 
66 then for a bit they stand face to face, play with their 
“ antennae, and seem to be all in all to one another.” 
Order, Diptera (Flies). — The sexes differ little in 
colour. The greatest difference, known to Mr. F. Walker, 
17 ‘ Transact. Linnean Soc.’ vol. xxvi. 1868, p. 296. 
