of Forficula auricularia in the Scilly Islands. 327 
still in progress, on the dimorphism of the forceps in the adult 
male. In the table showing the proportions of the sexes in collec- 
tions made up to 1911 the extreme instances are both from the 
Scilly Islands; Round Island, the granite islet at the north of the 
group, having 1671 per cent. of males; while the comparatively 
large and cultivated island of Tresco has the highest male per- 
centage so far observed, viz. 59-7. Both collections were made in 
August and September 1911. Mr E. J. Burgess Sopp, F.ES,, 
had kindly sent me the sex proportions of several collections made 
by himself in four English counties, and in his list also Tresco 
has the highest male percentage, 55°5 (collection made in 1903). 
In view of these results I went to the islands in the second 
half of August in 1912, in company with Mr F. A. Potts of Trinity 
Hall and Mr J. T. Saunders of Christ’s College, to whom I am 
indebted for great assistance in the task of collecting as many 
earwigs as possible. Collections were made in all the inhabited 
and in five of the uninhabited islands. We have to thank 
Mr T. Algernon Dorrien-Smith, the Lord Proprietor of the islands, 
for his kind hospitality and for local information which much facili- 
tated the earwig collecting and the other zoological work which 
partly occupied the time of Messrs Potts and Saunders. 
The figures in the sketch map show the percentages of males 
in the collections made in August 1912, and also in one islet, 
Rosevear, which we did not visit, and in one locality, Porth Cressa, 
the S.W. inlet of St Mary’s. These were searched for me by our 
boatman and his family in September 1913. The following table 
includes the collections shown in the sketch map and also all 
others from the Scilly Islands which are in my hands. 
From certain of the islands the total number of adult speci- 
_ mens is too small to accept the proportions of the sexes calculated 
therefrom without reserve. It has been a frequent experience 
that the proportions vary a good deal when the sexes are taken 
haphazard from a collecting bottle in which they have been mixed 
together, at least until a total of 300 has been exceeded. But on 
the islands which yielded a low total it was obvious that prolonged 
search would be necessary to capture say a thousand adults. A 
little experience keeps the searchers to the right spots and we left 
the smaller islands feeling that the hunt had been thorough: our 
boatman and his son were provided with a killing bottle on each 
occasion and they added considerably to our collections. 
If we set aside the islands in which the total number of adults 
collected is less than 300, there is still much evidence that the 
proportions of the sexes vary widely, and in the group as a whole 
the range is as considerable as in collections made in Great Britain 
in localities between Edinburgh in the north and Poole Harbour 
and West Cornwall in the south. 
