176 CHARACTERISTICS OF THE LIBELLUL&. 



But now let us consider by what characteristics the reader 

 is to recognise his Libellulse. 



The eyes are very large, the size of the insect considered ; 

 of a brown colour, and nearly joined together at the top of 

 the head ; in front of this point of junction a tiny vesicle is 

 visible, carrying three ocelli (i.e., little, simple, glossy eyes), 

 two on each side, and the third on the anterior margin: 

 the thorax is large, hairy, and composed of two yellow plates ; 

 the abdomen laterally depressed, in such a manner as to give 

 great prominence to the medial line. This last and well- 

 marked feature it is which has procured for the Eleanora the 

 scientific name of Libellula depressa, a name proposed by Lin- 

 naeus, and unanimously adopted ; such unanimity being a rare 

 occurrence among naturalists, though, to parody a phrase of 

 Sheridan's, when naturalists do agree, it is something wonderful ! 



In the male Libellulae, the upper surface of the abdomen is 

 bluish in hue, and covered as it were with an ashy dust, 

 while in the female it is olive; in both sexes the first and 

 last abdominal segment are of a deeper shade than the other 

 segments. The feet are black, and bristle all over with stiff 

 hairs ; the thighs are of a brownish red. The two pairs of 

 wings, each strongly reticulated, present, towards the extremity 

 of the upper border, a black rectangular spot; their base, 

 moreover, is edged with brown spots ; the spots of the lower 

 pair are triangular and larger than those of the upper pair, 

 which are nearly linear. They form, to a certain extent, the 

 reservoir of the liquid which nourishes and maintains the 

 circulation of the network of the wings. 



