BY R. J. TILLYARD. 323 



value than the usual "linear" grouping of genera. If an attempt 

 be made to unravel the phylogeny of the CorduUince on the same 

 lines, the genus Si/nihemis might either be placed at the base of 

 the Macromian group, or it might be deemed worthy of a separate 

 group, in which the genera to be proposed as subdivisions of it 

 in tliis paper will also be foi*nd to be of distinct phylogenetic 

 value. 



Let us now turn our attention to the larval forms of Synthemis, 

 the discovery of which should, I think, supply us with evidence 

 of at least coordinate value to that of the wing- venation. 

 (Descriptions of the larvas of five species of Synthemis will be 

 found below, pp. 340, 348, 355, 363, 370.) 



The line of specialisation so well known in Gorduline nymphs, 

 viz., the rounded and smooth bod}--, somewhat triangular and 

 pointed front to the head, and long spider-like legs, is found 

 developed to its greatest degree in nymphs of Macromia and 

 allies. In these nymphs the abdomen is almost circular in out- 

 line; the hea,d has developed a prominent frontal horn of pyra- 

 midal form; and the legs are exceedingly long. Now if Synthemis 

 were really so close an ally of Macromia as has heen supposed, 

 we should expect a somewhat similar larval development. But 

 the contrast between the nymphs could scarcely be more striking 

 than it is. The nymphs of Synthemis are absolutely unlike any 

 other known Cordidine nymphs. Their principal characteristics 

 are — an elongate-oval body, exceedingly villose; strongly diver- 

 gent wing-cases; head very square in front, with small prominent 

 eyes projecting from the antero-lateral angles; and rather .short, 

 thick legs. Tiie general shape of the nymph, especially the head, 

 recalls at first sight the Orthetrum-gvoup of larvae in the sub- 

 family Lihellulincs. But as these two groups are quite distinct 

 in such important characters as the labium and form of wing- 

 cases, it is probable that a great deal of superficial resemblance 

 is simply due to the convergence of adaptive characters, brought 

 about b}'' similar conditions of living. 



The nearest ally to the larva of Synthemis is most certainly 

 that of the European and American genus G or duleg aster. Thanks 



