598 NEUROPTERA. 



densely reticulated, very equal in size, and in some cases the 

 hind wings are a little larger than the fore wings. The tarsi 

 are three-jointed, and the second abdominal segment of the 

 males is furnished with accessory genital organs. 



4 ' Landois notices a peculiar sound-producing organ in this 

 family, and figures that of .ZEschna juncea. It is situated in 

 the prothoracic stigmata, which are placed quite at the front 

 of the thorax, and concealed by the head. These stigmata are 

 large elongated slits, one margin of which is simple, whilst 

 the other bears a sort of chitinous comb of about twenty teeth, 

 between which an exceedingly delicate membrane is extended. 

 The metathoracic stigmata, which in general are the chief or- 

 gans of sound in this part of the body, are smaller, and bear 

 on one side a semilunar valve with stiff hairs." (Giinther's 

 Zoological Record for 1867.) 



"During the pairing of the sexes, which takes place during 

 flight, the male seizes the neck of the female with his anal 

 claspers ; the female then curves the end of its abdomen to 

 the second abdominal ring of the male, which has a swollen 

 expansion of the under surface, containing in a longitudinal 

 cleft the intromittent organ, which conveys the seminal fluid 

 from the bladder-like cavity into the body of the female. But 

 since the outlet of the testicle opens on the ninth segment 

 of the abdomen, the males previous to union with the other 

 sex, must fill the copulating sac with the seminal fluid, by 

 curving its abdomen upon itself. After the union has been 

 effected the females generally let go of the males. In many 



the second or subcostal series); sss, postcubitals. Areas and Angles. t, the 



triangle (discoidal) ; u, internal triangle ; V, anal triangle ; W, basal area (or space) ; 

 xx, median area (or space); y, membranule ; z, anal angle in the male, the dotted 

 line z' showing the form of the anal corner of the wing in the female Gomphu;. 

 (The angle z ought to have been engi-aved as much more acute and salient.) A A, 

 discoidal areolets (in the figure two ranges of them commencing with three). 

 B, pterostigma; C, its basal (or internal) side prolonged in the normal manner; D, 

 " quadrangle," " quadrilateral," or " area above the triangle," bounded above by 

 m, below by d, basally by g, and terminally by an unnamed cross-vein; EEE, 

 postcostal area (or space). 



Of the above pterological parts, q and its sectors, r, s, t, W, y, B, and in the 

 Calopterygina and Agrionina "the quadrilateral" (D), and " the postcostal area" 

 (E), are the most important in classification. From Hagen with modifications by 

 Walsh. Following the nomenclature adopted in this work, aa would indicate 

 the marginal vein; b, the costal; c, the subcostal; d, probably the median, and e, 

 the submedian vein. 



