388 gundlach's work on the odonata of cuba 



The smaller size: abdomen (excl. apps.) cf 43-44.5, 9 45^6; sup. apps. 

 cf 6, (those of 9 broken); hind wing cf 42-43, 9 43-46; costal edge of stigma, 

 front wing, cf 9 3.5—4 mm. 



Fewer cells in the wings: e. g., between the lower branch of Rs and Rspl. 

 at the widest part, three or four (five in one 9 ) rows of cells vs. five or even six 

 rows in nervosa; hind wings between M4 and Mspl. at the widest part three 

 rows, occasionally four (cT) or five ( 9 ), vs. four to five rows (or even six in 9 ) 

 in nervosa. 



Differences in the genital armature of the second abdominal segment of the 

 male and of the hind end of the abdomen of the female, which require further 

 explanation. 



The genitalia of the second abdominal segment of the males of 

 these four species of Gynacantha are in most respects quite similar. 

 In all of them the ventral margins of the tergite of two, seen 

 ventrally, converge from the anterior end of the segment to, or 

 near to, the level of the hind edge of the auricles, thence they 

 diverge more slightly to the hind end of the segment. The extent 

 to which these ventral margins are approximated or divaricated 

 determines, of course, the degree to which the genitalia are visible, 

 especially the posterior hamules. In all four species, the anterior 

 lamina is deeply divided for its whole, or almost its whole length 

 by a deep sulcus. Each half of the lamina bears a well developed 

 spine directed caudad. The anterior hamule has a hamular 

 process and a hamular fold, using Dr. Walker's terms. The 

 hamular process is usually of a darker color than the surrounding 

 parts, is lamellate in form and bent into two parts or branches; 

 the plane of the anterior part is roughly longitudinal and 

 sub vertical, that of the posterior part is roughly sub vertical 

 and subtransverse (c/. plate XXXIV, fig. 34). The hamular fold 

 is visible in ventral view in all four species, lying posterior 

 to the hamular process. 



The ligula of Rathke and of Erich Schmidt (sheath of the penis 

 of Rambur and of other writers) bears a long, acute, median keel 

 directed cephalad and appearing, in ventral view, as a spine. 

 Viewed ventrally, the penis being retracted into the genital fossa, 

 the ligula, posterior to the keel, is subequal in width throughout 

 its length in trifida and septima, while in ereagris and nervosa it 

 widens markedly caudad (c/. plate XXXIV, figs. 31, 32, 34). 



Such other differences in the genitalia of these four species 

 which I have detected are as follows : 



trijldd (Plate XXXIV, fig. 34.) 



cT. Ventral margins of tergite of two with no sut)inargiiial dciiticlos. 



