Erythromma. 251 



which is stout ; the branch trachea; have their smaller 

 branches conspicuously dark in colour and arborescent 

 in structure. The end of the tenth segment is surrounded 

 with small points, and between the dorsal and each of 

 the lateral lamelhe is a small conical projection. These 

 nymphs are extremel}- livel}-, swimming b\' a sinuous 

 lateral motion of the bod}-. When thus progressing, 

 the lamella; are closed, and the legs brought close to 

 the side and stretched out at full length backwards ; 

 when walking, however, the legs are arched and the 

 thorax is raised. On being first taken from the water, 

 or if disturbed, they often feign death for a time. 

 [From Surrey specimens, bred on several occasions.] 



Date. 



In Surre}' the earliest date recorded for the imago is 

 May 6 (C. A. Briggsj, and I have found it m\'self on 

 July 16, when it did not appear to have reached the 

 end of its season. It occurs in France as late as 

 September. (De Sel}-s.) 



Habits. 



On the wing the appearance of the male reminds one 

 of /. clt'gdHS, and it might casil}' be passed over for 

 that species. It is, however, more robust, perhaps flies 

 more rapidh', and seems to be rather easily frightened. 

 The female, which is comparatively seldom seen, might 

 be confused with man}' of the darker Aon'oi/idiC. The 

 males often settle on floating weeds, such as Potamogcton. 

 When immature, E. naias should be looked for on the 

 bushes and herbage in the neighbourhood of its early 

 home. 



