2 INTEODUCTIOIS'. 



case where single females have been described, since, without an 

 examination of the male, it is impossible accurately to determine 

 the aiRuities of a species of earwig. It is also encouraging to 

 collectors to know that species new to science are being con- 

 tinually discovered. Hardly a collection, however small, is sent 

 to England for determination that does not contain one or more 

 undescribed species. 



It is to be especially hoped that entomologists in the field, 

 having now a means of naming their specimens, will be induced 

 to observe the bionomics — the true Natural History — of Earwigs. 

 There remains a very great deal to be done that may be easily 

 accomplished by a careful observer, even if he makes no claim 

 to be a systematist or a specialist. The interesting notes of 

 Dr. Annandale, in these pages, and, above all, the classic ob- 

 servations of Mr. Green on DipJatys, are encouraging examples 

 of this. As instances of work that may be well carried out in 

 India, the following lines of research are suggested : — The post- 

 embryonic development of Apachyvs and Pygidicrana compared 

 with Diplatys; the variation of the allied species of Forficida', 

 the semi-aquatic habits of Forciptda ; the elucidation of the 

 numerous and subtle species of Diplatys ; the vertical distribution 

 of the mountain-loving forms, such as Allodalilia, EndoJirnia, &c., 

 and why these have deeply tinted wings ; the discovery of the 

 males of those species of which only the females are known : 

 earwigs are frequently accused of damaging flowers by devourg 

 the petals ; has this been proved ? Probably they are omnivorous ; 

 they are known to be largely carnivorous ; are they entirely so ? 

 These and many other problems await solution. 



Str7(cture. 



The Jiead is more or less heart-shaped, varying from almost 

 triangular to pentagonal ; the posterior margin is generally trun- 

 cate, but sometimes emarginate in the middle. The head is 

 divided dorsally by a transverse sritnre between the eyes into 

 the frons or anterior portion, and the occijmt or posterior portion, 

 the latter being divided by a median suture which runs from the 

 middle of the ti-ansverse suture to tlie posterior margin of the 

 head. In some earwigs the head is smooth and tumid, so that 

 the sutures are scarcely discernible ; in others the sutures are 

 profoundly marked and very distinct. The form of the head 

 offers useful specific characters in the genus Di^datys, where the 

 frons is often tumid and the occiput depressed, while an oblique 

 keel runs from the eyes to the posterior margin of the head, but 

 these characters are scarcely developed in the females. The 

 mouth-parts offer practically no characters of any value to the 

 systematist. The eyes are large and prominent in Diplatys and 

 some Brachylahina', but are generally small, and ocelli are not 

 present. 



