Vol. xxvii] ENTOMOLOGICAL NEWS. 325 
EXPLANATION OF PLATE XVII. 
Figs. 1, 2 and 10. Acanthagrion adustum, type ¢ and 2, Wismar, 
British Guiana, Feb. 15, 1912. 1 and 2, appendages of ¢; 10, 
portion of right dorsum of thorax of 9, showing the mesepis- 
ternal fossa and mesostigmal lamina. 
Figs. 3, 4 and 7, appendages of ¢ of Acanthagrion indefensum, type, 
Wismar, British Guiana, Feb. 16, 1912; 7 posterior view. 
Figs. 5, 6, 8 and 11. Acanthagrion kennedi, type 6 and 2, Cumuto, 
Trinidad, March 10, 1912. 5,6 and 8 4,8 posterior view; 11 ?, 
same as IO. 
Figs. 9 and 12. Acanthagrion “gracile.” 9, posterior view of ¢, Morales, 
Guatemala, ‘May 27, 1909; 12, same as 10, 2, Gualan, Guatemala, 
June 10, 19009. ¢ 
Fig. 13. Acanthagrion ascendens. Same as 10, 9, Georgetown, Brit- 
ish Guiana, January 27, 1912. 
Notes on the Penes of Zygoptera (Odonata). 
No. 1. Species Limits in the Genus Acanthagrion. 
By CLARENCE HAmiLton KENNEDy, Cornell University. 
(Plate XVIII) 
In the fall of 1913, when I was working with the Argias 
and Ischnuras of Washington and Oregon’ I discovered that 
the penis, hitherto overlooked by systematists who had studied 
the Zygoptera, was in some cases an excellent generic char- 
acter and in other cases even a good specific differential. In 
the Fall of 1914, when I was working over my collection of 
California Odonata and found it expedient to describe two 
new genera, I went into a careful study of the penis in these 
and related genera, which convinced me that the penis had 
characters worth studying and made me desirous of carrying 
the study further. This opportunity came in the Fall of 1915, 
when I had the privilege of spending several weeks studying 
with Mr. E. B. Williamson in his private collection and 
laboratory at Bluffton, Indiana. At this time I drew two 
ata) of Washington and Oregon, C. H. Kennedy. Proc. U. S. Nat. 
Mus., Vol. 49, pp. 250-345, 1915. . 
?"Notes on The Life History and Ecology of The Dragonflies 
(Odonata) of Central California and Nevada. (In press.) 
