304 INTRODUCTION TO ZOOLOGY chap. 



legs. The eyes are farther apart and the head squarer than 

 in Aeschna. 



Fig. 226.^-LibeUida depressa. 

 n, Node of the wing. 



The larvae of these Dragon-flies are usually to be found 

 in very dirty stagnant water. 



Genus 1. Llbellllla. — Abroad-bodied form, witb a dark triangular 



stain at the base of the hind 

 wings ; the abdomen is not 

 spotted dorsally and it is 

 thicker in the middle, so 

 that its sides are not parallel. 



In L. depressa (Fig. 226) 

 the body is blue in the male 

 and brown in the female ; in 

 L. quadrimaculata, a very 

 common species, there is a 

 dark spot at the node of 

 each wing as well as at its 

 apex, and both sexes are 

 brown. 



Genus 2. Sympetrum. — Smaller forms than Libellula, with 

 narrower abdomen, and wings without the dark tri- 

 angular stain at the base, though, a yellowish stain 

 may be present. The male, except in the black species, 

 S. scoticum, is marked with brilliant red pigment 

 which is absent in the female. 



Fig. 227. — Nymph of Libellula. 



The line to the left shows the 

 actual length. 



