SECT. VIII.] 



INTRODUCTION. 



41 



STEVENS 1 though by later authorities 2 the species has not been 

 retained. A large sample of Earwigs collected in a Cambridge 

 garden contained 163 males of which 5 would come into the 

 high class, but the great abundance of high males at the Fames 

 seems to be quite exceptional. 



With a view to a statistical determination of the frequency of 

 the high and low forms 1000 of these Earwigs were collected by 

 Miss A. Bateson, the whole being taken at random on one day 

 from three very small islands joined to each other at low tide. 

 Of the 1000 specimens 583 proved to be mature males with elytra 

 fully developed, no specimen with imperfect elytra being included 

 in this number 3 . On measuring the length of the forceps to the 

 nearest half mm. and grouping the results in the graphic method 

 the curve shewn in Fig. 4 was produced. The figures on the 



FIG. 4. Curve shewing frequency of various lengths of forceps of male Earwigs 

 (F. auricularia) from the Fame Islands. Ordinates, numbers of individuals: 

 abscissas, lengths of forceps in mm. 



ordinates here shew the numbers ot individuals, those on the 

 abscissae giving the length of the forceps in millimetres. As there 



1 STEVENS, Brit. Ent. 1835, vi. p. 6, PI. xxvm. fig. 4. 



- FISCHER, Orthop. Europ., 1853, p. 74; BRDNNER VON WATTENWYL, Prodi: d. 

 europ. Orthop., 1882, p. 12. 



:i For particulars in evidence of the maturity of these specimens see P. Z. S., 

 1893. 



