Vol. xxiii] ENTOMOLOGICAL NEWS. 295 
superior appendage of the male is received into the socket on 
each side of the posterior surface of the female’s occiput, 
and that the dorsal tooth of the same appendage is braced 
against her prothorax. E. tristani therefore furnishes one of 
the most complex structural mating adaptations hitherto no- 
ticed in the Anisoptera. In looking over the plates of de Selys 
& Hagen (1858) nothing so complicated is to be found in 
any species of this family figured therein.* 
LITERATURE QUOTED. 
Catvert, P. P. 1901-1908. Biologia Centrali-Americana. Insecta 
Odonata. London. 
Ip, 1906. Copulation of Odonata. Ent. News, XVII, pp. 148-150, 
pl. VII. 
DE SELYs LonccHAmps, E. et. HAacen, H. A. 1858. Monographie des 
Gomphines. Bruxelles, Leipzig, Paris. 
WatLkER, E. M. 1912. The North American Dragonflies of the Genus 
Aeshna. University of Toronto Studies. Biological Series, No. 11. 
WriAMson, E. B. 1899. A Note on Copulation among Odonata. 
Ent. News, X, pp. 42-43. 
Wiriamson, E. B. 1906. Copulation of Odonata. Ent. News, XVII, 
Pp. 143-148. 
EXPLANATION OF PLATE XVII. 
All the figures are of Erpetogomphus tristani n. sp. and have been 
drawn with the aid of the compound miscroscope and camera lucida. 
The magnification is the same in all, x 12. 
Figs. 1 and 2. Dorsal and anterior views respectively of the vertex 
and occiput of the male. The dotted line in 1 shows the boundary be- 
tween green and black on the superior surface of the frons. 
Figs. 3 and 4. The same of the female. g, the vertical groove, mo, 
median ocellus. 
Fig. 5. Left profile view of the apex of the male abdomen. 
Fig. 6. Dorsal view of the superior abdominal appendages of the male. 
Fig. 7. Ventral view of the inferior abdominal appendage of the 
male. Dotted lines show the proximal parts of the superior appendages. 
oe 8. Left profile view of the inferior abdominal appendage of the 
male. 
Fig. 9. Right profile view of the genitalia of the second and third 
abdominal segments of the male. p, posterior hamule and s, sheath of 
the penis, separated from the rest, p in lateral, s in posterior view. 
Fig. to. Ventral view of the oth, and adjoining parts of the 8th 
and roth, abdominal segments of the female. 
*Since this paper was written, Dr. E. M. Walker’s superb monograph 
of the North American Aeshnas has appeared (1912), in which he dis- 
cusses (pp. 39-42) and figures (Plate 2) the copulatory position of 
Aeshna, Gomphus and other Odonata. 
