1892.] VARIATION IN SECONDARY SEXUAL CHARACTERS. 587 



shall refer to these two forms as " high " and "low " males respec- 

 tively. 



It appears that the high male is known from many places in 



Forficula auricularia, the Common Earwig. 

 I. Low male. II. High male, 



England and elsewhere, and that it was made into a distinct species 

 by Stephens^ under the name F. forcipata. This species has not 

 been retained by later authorities (see Fischer ^ and Brunner von 

 WattenwyP). After the visit to the Fames, the liigh males were 

 found on the mainland near Bamborough in fair quantity, though 

 not so abundant as on the Fames. We have received also a large 

 sample of Earwigs collected in a Cambridge garden, containing 163 

 males, of which 5 would come into the "high" class. A 

 sample kindly collected for us bj Dr. Norman, F.R.S., in his garden 

 at Burnmoor, near Durham, contains no high male. The great 

 abundance of high males at the Fames seems to be quite excep- 

 tional. 



Witli a view to determining the frequency of the high and low 

 forms, 1000 of these Earwigs were collected for us by Miss A. 

 Bateson on Sept. 12, 1892. The whole were taken in one day from 

 three very small islands known as the Knocksies and Widerpern, 

 which are joined to each other at low tide. 



Of the 1000 specimens 583 proved to be mature males. Before 

 giving the results of the measurements, it is perhaps necessary to 

 give the reasons upon which we believe these specimens to have been 

 all adult. In this matter we rely partly on the judgment of 

 Dr. Sharp, F.R.S., who has most kindly assisted us in many ways 

 throughout this investigation, and was so good as to take part in 

 the work of measurement. We are informed by Dr. Sharp that the 

 full development of the elytra is only reached in the adult state in 

 F. auricularia, and we have been careful to include no specimen 

 having imperfect elytra. As may be seen in the figures, the develop- 

 ment of the elytra in the high and low males is the same. Besides 



^ 'British Entomology,' 1835, vi. p. 6, pi. xxviii. fig. 4. 

 2 'Orthoptera Europaja,' 1853, p. 74. 

 ^ 'Proclr. d. europ. Orthop.,' 1882, p. 12. 



