. 469 



The species is apparently rare in Illinois though reported from 

 this state by Williamson (oo). The above description was made from 

 three specimens in the collection of the Illinois State Laboratory of 

 Natural History, two of which bear the label "Mass.". I have not 

 seen the species within the state. 



Agrion maculatum Beauvais 



Nymph. — Color, dark brown. 



Head pentagonal, little contracted behind the eyes; eyes black, 

 a black stripe nearly the width of the eye extending to the caudal 

 margin of the head, and another stripe extending from the antennal 

 fossae to the eyes; proximal segment of the antennae thick, about as 

 long as the head, and usually slightly longer than all the remaining 

 segments together; labium with the median lobe deeply cleft, the 

 cleft extending proximad of the articulations of the labial palpi (Fig. 

 8) ; proximal segment of the palpus with three immovable end-hooks 

 and two small setae near the base of the distal segment of the palpus. 



Thorax : prothorax with a broad dark line on each lateral margin 

 which is continuous with the dark line on the side of the head ; legs 

 slender, the femora with a whitish band on the apical third, with 

 a narrower brownish band proximad of the white one, and a distal 

 brownish band extending to the apex of the segment; tibiae without 

 heavy setae ; tarsi short ; wing-cases broad and extending in full- 

 grown nymphs as far as the fourth abdominal segment. 



Abdomen subcylindrical, dark, and without distinct lateral keels; 

 apical margins of the terga with about four dark spots on the dorsum ; 

 lateral tracheal gills three-sided, somewhat blunt, with a white trans- 

 verse band near the middle of their length; median gill flat, shorter, 

 with a similar cross-band at the middle and another faint band beyond ; 

 marginal setae of the median gill long and slender, extending entirely 



around the gill. 



Measurements 



Length 20 mm. 



Length of abdomen 15 mm. 



Length of lateral gills 10-12 mm. 



Length of metathoraeie wing-cases 6 mm. 



Length of median lobe 4.5 mm. 



Width of median lobe 1.3-3 mm. 



Adult; Male. — Color, metallic green or blue. 

 Head green ; labium black, the median lobe subtriangular in out- 

 Hne, the cleft extending slightly less than half the distance from apex 



