324 MONOGRAPH OF THE GENUS SYNTHEMIS, 



to the kindness of Dr. Ris, I hav'e been enabled to study, from 

 his own excellent photographs, the nymph of Corduleyanter 

 annulatus, the commonest European species. The I'esemblance 

 between it and the nymph of Synthemis eustalacta, for instance, 

 is extraordinarily close. In both nymphs the head is of the same 

 shape, with .square front, prominent' eyes, and rounded hind-lobes; 

 the wing-cases of both are strongly divergent; the legs of ])oth 

 are much shorter, in proportion to the size of the larva;, than in 

 any G ordidine nymph; the abdomens of both are villous, elongate- 

 oval, and rather rounded than flab underneath. Tn general 

 appearance the Syntheviis n3'mph is shorter and broader — more 

 thickset — than the Cordidegaster nymph; but this is almost the 

 only difference. 



In Gordulegaster the antennfe are seven-jointed, with two basal 

 joints thickened and rather rounded, the other five being filiform. 

 The same is true of the antennte of Synthemis(&ee Plate viii., fig. 4), 

 which are also very hairy. (I cannot say, from the photos, 

 whether those of Gordulegaster are also hairy, but it is highly 

 probable in so villous a nymph). 



A comparison of the labia of the same two nymphs shews that 

 both are of the recognised Gorduliiie form, with sub triangular 

 mentum, broad lateral lobes, furnished with a terminal spine, and 

 strongly dentate along the distal border. Large sette are also 

 developed both on the mentum and on the lateral lobes. The 

 dentition of Synthemis eustalacta (ace Plate ix., fig. 1) is much 

 smaller and more regular than tliat of Gordulegaster, tlie nearest 

 approach to which may be seen in Synthemis niacrostigma (Plate 

 ix., fig. 3). In the position of rest, the labium is similar in both, 

 the mentum and lateral lobes forming together a large cup-shaped 

 or almost hemispherical cover to the underside of the head (see 

 Plate viii., fig. 3). 



This remarkable similarity between the nymphs of Synthemis 

 and Gordulegaster is of great phylogenetic importance, for it 

 supplies the missing link between the two great divisions of the 

 Anisoptera — the ^Eschnidoi and Libelhdidce. Of the jEschnidoi, 

 Gordulegaster alone — shewing no trace in its imaginal develop- 



