308 THE ENTOMOLOGIST. 



the first ease, where the females are in a great minorit}', only a 

 very small selection of males is made for pairing, and the laws 

 of chance cannot be applied to ver}^ small selections. 



Make up, for instance, a pack of cards with 52 red and 26 

 black. The chances are then 2 to 1 on any card being red. Try 

 to verify these chances, first by selecting at random 3 cards, and 

 noting down their colours ; repeat this process several times, 

 putting back and shuffling the three cards after each draw. 

 Then try with larger and larger selections in the same manner, 

 and see which give the nearest result to the proportion 3 red to 

 1 black on the total number of draws. If this does not satisfy, 

 the experiment may be tried with more complicated proportions. 

 With more complicated proportions, larger draws are required, 

 and so on. It is to a similar principle that a gambling establish- 

 ment like Monticarlo owes its continued existence. 



Some way back (p. 280) the principle was formulated that 

 equality in the number of the sexes tended towards equilibrium, 

 and that inequality tended towards fluctuation of characters. 

 To illustrate this, an hypothetical case was taken (1) in which 

 the males were variable and the females constant, the males 

 being in excess. It is plain that several other conditions might 

 occur. Thus (2) males variable, females constant, females in 

 excess ; (3) males constant, females variable, males in excess ; 

 (4) males constant, females variable, females in excess ; (5) males 

 variable, females variable, males in excess ; (6) males variable, 

 females variable, females in excess. By a little consideration it 

 will be seen that conditions (2) and (3) are favourable to an 

 equilibrium being established, and therefore do not fall in with 

 the principle, and that (1), (4), (5), and (6) are conditions 

 favourable to fluctuation. The second clause of the principle 

 formulated must therefore be narrowed to the following — "and 

 that inequality when coupled with variability in the prepon- 

 derating sex tends towards fluctuation." 



(To be continued.) 



NOTES ON THE DIVISION VELIIARIA [EHYNCHOTA] 



( = SuBFAM. VELID^, Leth. & Sev.). 



By G. W. Kirkaldy, F.E.S. 



(Continued from p. 286.) 



The following table of species is to some extent based upon 

 Champion's table of Central American species ; I have, however, 

 seen specimens of most of the described species : — 



1. Posterior tibiae with a long hook at the apex. 



[Posterior femora, moderately incrassate, dentate] . . 2 



la. Posterior tibiae without a hook ..... 4 



2. Terminal genital segment mucronate . 1 nncinata, Champ. 



