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 he found in 

 any species of this family figured therein.* 



LITERATURE QUOTED. 



CALVERT, P. P. 1901-1908. Biologia Centrali-Americana. Insecta 

 Odonata. London. 



ID. 1906. Copulation of Odonata. Ent. News, XVII, pp. 148-150, 

 pi. VII. 



DE SELYS LONGCHAMPS, E. et. HAGEN, H. A. 1858. Monographic des 

 Gomphines. Bruxelles, Leipzig, Paris. 



WALKER, E. M. 1912. The North American Dragonflies of the Genus 

 Aeshna. University of Toronto Studies. Biological Series, No. n. 



WILLIAMSON, E. B. 1899. A Note on Copulation among Odonata. 

 Ent. News, X, pp. 42-43. 



WILLIAMSON, E. B. 1906. Copulation of Odonata. Ent. News, XVII, 

 pp. 143-148. 



EXPLANATION OF PLATE XVII. 



All the figures are of Erpetogoinphiis 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, i and 2. Dorsal and anterior views respectively of the vertex 

 and occiput of the male. The dotted line in i 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. 



Fig. 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. />, posterior hamule and ^, sheath of 

 the penis, separated from the rest, p in lateral, j in posterior view. 



Fig. 10. Ventral view of the 9th, and adjoining parts of the 8th 

 and loth, 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. 



