160 Annals of the Carnegie Museum. 



strong acute spine, which is curved anteriorly (cephalad) at its tip ; 

 this spine is concealed by the inferior appendage of the same side of 

 the body, lying laterad to it in an ordinary profile view. Inferior 

 appendages shorter than the superiors, higher than long in profile 

 view, upper edge produced backward (caudad) and slightly upward 

 to an acute apex, which reaches beyond the level of the rounded 

 postero-inferior angle of the appendage, distal edge concave. 



Legs obscure brown, femora darker, 7-8 spines on the outer row of 

 the third tibia. 



Wings uncolored, stigma dark brown, surmounting one cell, its 

 costal edge very little longer than the proximal or distal edges ; three 

 antenodal ultraquadrilateral cells on all wings, anal vein ( = inferior 

 sector of the triangle of de Selys) parting from the hind margin 

 proximal to the cubito-anal ( = basal postcostal of de Selys) cross- 

 vein on the front wings by a distance almost as great as the length of 

 the cross-vein itself, on the hind wings by a distance distinctly less 

 than the length of the cross- vein. Front wings with 12-13 post- 

 nodals ; M 2 ( = nodal sector of de Selys) arising at the fifth. Hind 

 wings with 10-11 postnodals ; M 2 arising at the fourth. 



Abdomen 30, hind wing 20.5 mm. 



9 unknown to me. 



Habitat : — Colombia, Santa Fe de Bogota, by Lindig, 1863, id\ 

 Museum of Comparative Zoology, Cambridge, Mass. 



The specific name is a manuscript name of Hagen's, under which 

 this specimen and a number of others have stood for many years. 

 These other specimens, male and female, are, with one exception, 

 very immature, and the males have lost the hind end of the abdomens. 

 A mature female differs in the shape of the pterostigma and in a 

 number of details of the venation. Taking these defects and differ- 

 ences into consideration, I am very doubtful whether these other 

 specimens also belong to ovigerum. 



Genus Acanthagrion. 

 The following synopsis will assist in the identification of the species 

 of the typical group of this genus, the group of gracile Rambur, which 

 agree in having the anal vein ( = inferior sector of the triangle of de 

 Selys) parting from the hind margin of the wing at, or distal to {not 

 proximal to) the cubito-anal cross-vein ( = basal postcostal of de 

 Selys) on all the wings. 



