Vol. xxiii] ENTOMOLOGICAL NEWS. 293 



Abdominal segment 2 with a mid-dorsal, and on each side a longitud- 

 inal, yellow stripe occupying the greater part of the length of the seg- 

 ment. Greatest width of the posterior half of the abdomen at the 

 articulation of 8 and 9. Auricles on 2 very much smaller and not dentic- 

 ulated, as usual in this sex. Segments 7-10 successively shorter. Mid- 

 dorsal posterior process of 9 shorter than in the male. Hind dorsal mar- 

 gin of 10 nearly straight, not produced. Eleventh segment a little 

 shorter than the tenth, its tergite and sternites sub-equal. Terminal 

 abdominal appendages as long as 10, pale brown, straight, conical, apices 

 acute. 



Vulvar lamina one-third as long as 9, its apical margin one-third as 

 long as its base, shallowly concave (Fig. 10). 



$ $ . Wings slightly smoky, tinged 'with faint yellow at the extreme 

 base. Front wings with 14 ($)-!$ (?) antenodals, 12-14 postnodals. 

 Hind wings with n antenodals, 12-13 postnodals, anal triangle of $ 

 3-celled. Stigma dark brown. 



Dimensions. Total length, $ 42, $ 44. Abdomen $ 31.5, $ 33.5. 

 Hind wing, $ 28, $ 29. Costal edge of stigma, front wing $ 3, $ 3.5. 

 Width of head $ 6, $ 6.3 mm. 



Hob. Costa Rica, Oricuajo (Pacific side), July, 1911, by 

 Prof. J. F. Tristan, i $ , i $ , now in the collection of the writer 

 at the Academy of Natural Sciences of Philadelphia. 



Type. The male above mentioned. 



This pair show the following differences from the generic 

 characters of Erpctogomphus as given in Biol. Centr.-Amer. 

 Neur., pp. 146-147: 



There are 9 (10 on the left side of the $ ) marginal cells on the 

 front wings between M4 and Cui (short sector and first sector of the 

 triangle) instead of 6-8 cells. I find in my notes, however, mention of 

 a female E. designatus from Texas with 9-10 marginal cells. 



There is but one row of cells in the anal and second cubital areas 

 (postcostal area of de Selys) of the front wings from the base to be- 

 yond the level of the triangle ; there are only two rows of cells at any 

 point between Cu2 (second sector of the triangle) and the hind margin 

 in the male, but there are three rows for three (right) or four (left) 

 cells in the female. These variations were met in the Biol. Cent. Amer. 

 material also. 



While the arculus is at or proximal to the second subcostal antenodal 

 in seven out of the eight wings, it is not necessarily at or proximal to the 

 level of the second costal antenodal, as the second subcostal antenodal 

 is not coincident with the second costal antenodal in six out of the 

 eight wings, but distal thereto. This lack of coincidence is often to be 

 seen in this genus. 



