26 MUSEO NACIONAL DE BUENOS AIEES. 



2. Acanthagrion latapistylum n. sp. 



(Fig. 1-3). 



One male and one female, although evidently related to A. gra- 

 cile Ramb., appear to be of an liitherto unnamed species. A des- 

 cription tberef ore f ollows : 



cf . Labrum (except a median, basal, black point), rliinariiim, an- 

 terior part of frons, rear of liead and labium palé green or yellow. 

 Nasus and vértex black, a pair of small j)ale dots on the nasus, 

 some small palé brown spots in front of the median ocellus and 

 near tlie bases of tlie antennae; tlie j)ostocular spots green, elon- 

 gate. 



Dorsum of protliorax black, sides yellow, a pair of exceedingly 

 small mid- dorsal palé spots: hind margin 

 rounded with a very slight median notcli. 



Dorsum of thorax witli a median and a 



humeral stripe (eacli side) black; tlie palé 



antebumeral stripe between them is lialf as 



wide as the mid -dorsal, the humeral is three- 



Fif/ 1 Dorsal viewof fo^^tlis as wide as the mid- dorsal. Sides of 



left superior appendage the tliorax colorless except for a very small 



of Aranthafjrion latapi- ^lack line uudcr each wing. 



*'"Thedon'efnine shows Dorsum of abdominal segments 1-7 and 



the upper boundary of 10 dark metallic green, almost black, wliich 

 the palé anteapical co- extends uninterruptedlv from base to apex 



loring. X60. . i o T. ^ • • ^ ^ i l 



on 1 and 2, but is mterrupted by a narrow, 



transverse, basal, yellow ring on 3-7; 8 and 9 blue but each with 



a very narrow, transverse, apical black line. Lower surfaces of all 



the segments yellow. 



Legs yellowish, femora superiorly and aj^ices of the tarsal joints 

 blackish. 



Apical margin of tenth abdominal segment with a mid -dorsal, 

 semicircular excisión one-third as deep as the lengtli of the seg- 

 ment. 



Superior appendages slightly shorter than 10, black, palé on 

 their iimer apical surfaces; viewed from above, divergent, enclosing 

 a semicircular interval, ápices rounded and obtuse; viewed from 

 the side, each appendage is gradually widened from base to apex 

 which is truncated almost at right angles to the upper and lower 

 margins of the appendage; the upper margin is convex, the lower 



