IXDIAX DRAGONFLIE^. 467 



opposing borders of the jiiws : that of tho Aoschninos bears a single tooth 

 shaped like a spine on either side of the jaws. These si)ine-like teeth are so 

 long that they cross and overlap each other across the middle lino and 

 almost conceal a pair of membranous, rhomboidal jaws placed below them. 

 The latter are furnished with fine teeth along their opposing borders and 

 that facing the body of tho mask. The mask of the Gomphines is mnch 

 bn)ader at the base than any other species and it is araied with large, biiid 

 jaws which are furnished with a row of sharp teeth or spines along their 

 inner border and which when at rest, cross each other in the middle line. 

 The mask of tho Cordulines is the most powerful and the most highly 

 developed. The basal part is triangular, the jaws when placed together 

 form a cup or basket of which the formidable rows of interlacing teeth 

 form the ribs. These jaws are sharply bent or angnlated, curving np, to 

 completely cover the lower part of the face. The function of the mask is 

 an exact parallel to that of the tongue of the chameleon. It possesses 

 two joints, one at its attachment to the mcnton and the other about its 

 middle which enables it to expand forward or to contract back, in which 

 latter situation, in the Libellulines and Cordulines, the cup-like mask 

 situated at its extremity, fits closely over the mouth and its contained 

 jaws. The free end of the mask is furnished with the jaws already des- 

 cribed, which fold in and out and when approximated, form a concavity 

 more or less deep according to the species. The function of this organ is 

 to seize insects on which the larva preys and to convey them to its mouth. 

 Normally when at rest the labium is kept carefully folded over the jaws 

 but should an unwarj^ insect pass in the vicinitj'^, it is shot out with 

 incredible swiftness and before one realises it, the insect is struggling in 

 the jaws of its captor. 



The prothorax and thorax are fused into one mass; the former being 

 narrower but mnch broader than in the imago. The thorax is small and at 

 first naked, there being no trace of wings in the first instar of the larva, 

 later however the wing-cases develop and in the final stage are present, 

 either as flat, earshaped objects in the Aeschuines and Libellulines and in 

 some of the larger Gomphines or as long, narrow, cylindrical objects in the 

 latter family. In the Libellulines the forewing-cases entirely cover the 

 hind but in the Gomphines the latter are situated internal to the fore. 



The ahdomen is made up of ten segments as in the imago and presents 

 wide dift'erences in shape in the different species. In the Gomphines it 

 may be long and somewhat tapering or short, squat and enormously 

 dilated. In the Aeschnines it is narrow, the sides parallel and spined, the 

 dorsum rounded: in the Libellulines there is always a certain amount of 

 dilatation and the dorsum is usually keeled. Larvte of the Cordidines 

 possess a comparatively short abdomen, greatly dilated and with great 

 development of the dorsal ridge. In some species, on each segment there 

 is a pair of pigmented spots which at first sight appear to be spiracles and 

 which possibly represent the site of atrophied spiracles. 



The anal end of the abdomen is furnished either with small valvular flaps 

 as in the Aeschnines, Libellulines, Cordulines, or with a tubular structure 

 formed from the juxtaposition of hollovved-out and modified valvular 

 flaps. This tube, in at least one species of (^omphine, is formed from the 

 last two abdominal segments and is remarkably long and slender with the 

 end bevelled oft' above in very much the same way as the point of a hypo- 

 dermic needle. These valves and tubular structures are connected with 

 the respiratory system of the Dragonfly and by their means, water is 

 sucked in and driven out of the rectimi. Normally the only means of 

 locomotion is by means of the legs which are long, especially so in the 

 Cordulines, and which do not difter markedly from those of the imago, 



