THE EARWIGS OF CEYLON, 61 



INTRODUCTION. 



The HEAD, in the Forficularia, is more or less flattened and heart-shaped. 

 It offers few characteristics which are of any value for specific distinction 

 except the number and form of antennal segments. These may vary from 

 9 to 30 in number, and form a useful generic character. The segments are 

 usually pear-shaped, or abruptly conical. G-reen has detected an oval 

 glandular (?) body on the under surface of each segment, its presence indicated 

 by a depression and a minute pore. This organ is visible from the earliest 

 stages and are most probably a sense organ of some kind. 



The PRONOTUM is small, either narrower or broider than the head, 

 more or less square in shape. The angles may be either rectangular or 

 rounded, and sometimes the anterior border of the pronotum is rounded, 

 soiiaetimes straight, as also the posterior border. A small SCUTELLUM 

 is visible between the elytra and the base in certain genera. The 

 MESO and META-NOTA are visible when the elytra are absent or 

 rudimentary. 



The ELYTRA are sometimes absent, and sometimes rudimentary, in 

 which case they are cemented to the thorax, and usually more or less 

 triangular in shape ; when they are perfectly developed tbey are small, 

 oblong, shining and veinless ; they may be rounded, emarginate or truncated 

 at the apex. 



The WING-S are voluminous and very delicate ; they are shaped like an 

 ear, and veined from the basis of a hard horny scale which occupies the 

 basal half of the anterior margin. From the apex of this scale the small 

 veins radiate fanwise, being crossed by a curved vein which runs completely 

 round the outer border, parallel AAith the outer margin itself. In repose 

 the wings are folded fanwise from the apex of the scale and then again at 

 right angles, being thus folded up extremely neatly into a very minute and 

 compact flap, which is covered by the small elytra, although these are about 

 half the size of the wings, or less ; when these organs are closed the horny 

 scale is exposed, and is often of the same colour as the elytra. In appearance 

 they resemble a second pair of elytra, and in repose they perform similar 

 functions. When wings are mentioned in descriptions it is this hard scale 

 that is meant, unless it is expressly stated otherwise. In very many cases 

 the wings are entirely absent. 



The STERNA are flattened plates. 



The ABDOMEN is the most conspicuous part of an earwig. The segments 

 are imbricated together in a beautiful and delicate manner. When the 

 abdomen is distended, and the uniting membrane drawn taut, the minute 

 spiracles are visible in the membrane. In some cases the second and third 

 dorsal segments bear at each side a small fold, or " stink-gland," which is a. 

 useful character. In the male there are nine segments, excluding the last or 

 anal segment ; in the female there are seven visible. Some species are armed 



