40 British Dragonflies. 



of certain species, of a projection at the base of the 

 upper anal appendage (Fig. ii, ;//./.)• ^ useful though 

 rather obscure point which assists in distinguishing the 

 species of the ^-EschnincB, is to be found in the relative 

 size of, and the angle between, a pair of processes at 

 the base of the forelegs. In Fig. 19 those of se\en 

 species are given. Though man}' of the nymphs at first 

 sight appear to be smooth, a closer examination reveals 

 the fact that they are all more or less covered with 

 points or hairs. In some of the Libclluliiuc the hairs 

 are long and numerous. Libcllula depressa is a good 

 example of a hairy nymph, while Anax iuipcrator is a 

 comparatively smooth one. 



TENTATIVE TABLES OF THE NYMPHS OF BRITISH 



ODONATA. 



Any attempt to give a satisfactory statement of the 

 points of differentiation of the nymphs of e\-en the 

 British Odoiiata cannot, with our present knowledge of 

 them, be very satisfactory. The families and sub- 

 families are fairl\- distinct, except in the case of the 

 LibclhilincB and Cordiiliiiue ; but it has been found 

 quite hopeless to satisfactorily tabulate the genera, and 

 this has not been attempted. The species, however, have 

 been diagnosed as far as circumstances would allow. 



I. — Table of Families. 



Body robust ; ahdomen widest near the centre, 

 and ending posteriorly in five caudal appen- 

 dages ; breathing by rectal branchi^. S^A)iis- 

 optcridcs\ 



a. Abdomen somewhat flattened and 

 much expanded at centre ; mask 

 spoon-shaped; eyes small, sub-conic, 

 projecting; legs longer than abdomen LniKi.i.ri.iu.'E. 



