BY R. J. TILLYARD. 331 



segments 9 and 10 with respect to 8. In some specimens, 

 especially ill-nourished ones, segments 9 and 10 are piled up 

 somewhat as in Forster's diagram, but I doubt if it ever is so in 

 a well-fed specimen, even of .S". primigenia. Though, in all those 

 species possessing an ovipositor, segments 9 and 10 are — seen 

 laterally — much narrower than 7 and 8, yet, in their proper posi- 

 tions, they lie in a line more or less parallel to, and above, the 

 ovipositor. Forster's diagram apparently I'epresents not only 

 an immature, but even a malformed or damaged specimen, for 

 the end abdominal appendages of segment 10 are entirely 

 Jacking I 



Variation of the Female Sex-Organs. — We shall see, from a 

 study of every species of Synthemis of which the female is known, 

 that there is an enormous difference in these organs, even in the 

 most closely allied species. There is no doubt that the ovipositor, 

 where still present, has ceased to be used for its original purpose, 

 i.e., no species of Syatheinis now uses its ovipositor as a terebra 

 or borer. I have watched five species of Synthemis ovipositing. 

 Three of these possess well-formed ovipositors — S. macrostiyma, 

 S. eustalacta, and S. Jlavoterminaia. All three lay their eggs iu 

 the Lihellulid manner, by flying close to the surface of the water,, 

 then hovering with body almost vertical, and dipping it with 

 short quick movements, three or four times in succession, into the 

 water, so as to wash the eggs out, several at a time. Females of 

 S. eustalacta, captured in the act of oviposition, have immediately 

 exuded clusters of eggs from ten to a hundred or more in number. 

 (A portion of one of these clusters is figured, greatly magnified, 

 in Plate viii., fig.l). Females of S. macrostigma, however, cap- 

 tured in the same way, exude only two or three eggs in a cluster^ 

 and sometimes none at all. These, also, sometimes support them- 

 selves by holding lightly to a reedstem, while still hovering with 

 their wings, and dipping their abdomens in the usual way. ^S*. 

 Jlavoterminata — and the two species, S, regina and S. guttata, 

 which do not possess ovipositors — all oviposit while flying rapidly 

 to and fro over the water, and wash out their eggs in large 

 clusters. 



