194 THE ZOOLOGIST. 



meeting with the graceful "Demoiselle." I have on two occa- 

 sions, however, taken it a long way from any water. Virgo is 

 subject to a considerable amount of variation. The female, as 

 a rule, has a white stigma on the fore wing, but frequently 

 this is absent altogether. The wings of the male are a deep 

 shining blue, and I once took a specimen with the left fore 

 wing almost white, though the others were of the normal 

 colour. This Dragonfly generally puts in a first appearance 

 the time the May-fly is "up." This and the next species are 

 the only British Dragonflies that retain their brilliant lustre 

 when dead. 



C diopter yx splendens (Harr.). — Unlike the last, this is 

 usually to be found either flying over or resting on the 

 rushes bordering still water. I have not found it nearly 

 so common as the last. 



Agrionid^. 



Erythromma ndids (Hans.). — This I have found the rarest of 

 Surrey Odonata, and have only taken it twice. 



Pyrrhosoma nymphula (Sulz.). — When depositing its ova, 

 this Dragonfly alights boldly on the surface of the water and 

 remains thus motionless with outspread wings for some time. 

 Occasionally it is accompanied by the male insect. I have 

 found the under side of the thorax in this species often covered 

 with a parasitic mite resembling those common on the Dor 

 Beetle. 



Lestes sponsa (Hans.), Agrion puelld (Linn.), A. pulchellum 

 (Lind.), and Ischnura elegans (Lind.), are all very common, 

 frequently being found consorting together. 



The above list must in no way be considered a complete one 

 of Surrey Dragonflies. Doubtless there are many others to be 

 added, but so far I have not been fortunate enough to come 

 across them. 



If the wing of a Dragonfly be examined under a microscope 

 with a one-sixth objective, the nervures will be found to be 

 covered with curious protuberances resembling thorns (cf. 

 'Zoologist,' 1908, pp. 458-9). I have often wondered as to 

 what could be the use of these " thorns," and at one time 

 thought they might act as a stiff support to the more delicate 



