502 PROCEEDIXGR OF TEE NATIONAL MUf^EUM. vol.52. 



siderably above the horizontal and wait in this position several seconds, 

 when the pair would fly to another straw and repeat the one or two 

 thrusts followed by the wait with the tip of the female's abdomen in 

 the air. (See figs. 60-61.) This was kept up, by a pair under observa- 

 tion, for 20 minutes. In no place did they make more than one or 

 two thrusts. Further, I was not positive at the time that the ovi- 

 positor was actually thrust into the plant tissue, as the females observed 

 put forth none of that painstaking effort usually shown by ovipositing 

 dragonflies. Later, when these grass blades were examined in the 

 laboratory, eggs were found in pairs (see fig. 59). This species is mi- 

 doubtedly the feeblest of all thewestern Odonata, not excepting Tele- 

 basis salva, which is no larger but much more active. 



Length of abdomen: Male, 19 mm.; female, 20. Length of hind 

 wmgs: Male, 12 mm.; female, 14. 



Male, structure. — Only 2 internal spines on anterior femur, one at 

 base, the other at apex. Hind tibia with 6 external spines. Hind 

 femur reaching to middle of segment 2. Wings reaching to middle of 

 segment 6. A low hairy prommence on ventral side of metathorax. 

 Segment 3 with a low spine at anterior ventral angle of side. Penis 

 (fig. 85) two-horned as m Ischnura but without the pair of erect 

 spines on the ventral side of the penultimate segment. The fleshy 

 tips but two-thirds as long as in gemina. Segment 10 with a raised 

 forked process on the middorsal apex. Appendages of segment 10 

 figs. 89-91) similar to those of gemina with the followmg differences: 

 The external branch of the superiors wantmg; the inferior-external 

 branch of the inferiors developed into a short upturned hook; the 

 dorso-lateral branch of the inferiors very short. Li denticollis the 

 inferiors project beyond the superiors. In gemina (fig. 95) the infe- 

 rior branch of the superior falls anterior to the superior process of 

 the inferior. 



Female, structure. — Similar to that of male except as follows: Pro- 

 thorax with the dorsum of the middle lobe with a pair of low conical 

 protuberances or horns. The posterior lobe romided and moderately 

 developed. (The only female with which denticoUis might be con- 

 fused is that of damula, which has the same two hoi-ns but the pos- 

 teriotlobe is reduced to a large tubercle projecting caudad.) (See 

 figs. 63, A-B.) (Mesotigmal laminae, fig. 88.) 



Anterior femora with but two internal spines, one at base and one 

 at apex. Posterior femora reaching to middle of segment 2. Wings 

 reaching to base of segment 7. Segment 10 half as long as 9; appen- 

 dages two-thirds length of 10. Segment 8 with minute spine.^ 

 Genital valve reaching to apex of 10, and minutely serrate along its 

 ventral margin. Palp two- thirds length of 10. 



1 Calvert has shown that as many as 80 per cent of the females from a locality may not possess this spine. 

 Biol. Cent. Amer., Neur., pp. 126, 387. 



