No. 39] ODONATA OF CONNECTICUT: AGRIONIDAE II5 



of 3-6 pale. Anal appendage with superiors about three times as 

 long as the blunt inferiors, and pale at bases, darker towards their 

 apices ; the ventro-mesal margins of each with two rounded lobes 

 just beyond the middle. 



Female. — Color bright metallic green, the bases of the wings 

 not carmine as in the male. There is considerably more pale color 

 on the thorax, and abdominal terga i-io are broadly margined 

 with yellow ; ovipositor yellow. 



Measurements : total length, male 44-46, female 40-45 mm. ; 

 length of abdomen, male 33-35, female 30-35 mm. ; length of hind 

 wings, male 28, female 28-30 mm. ; width of hind wings, male 

 5.5, female 6-6.5 mm. ; length of pterostigma, male and female 

 .5-1 mm. 



Connecticut. — Kent, 31 August, 1904 (W. E. B.) ; Windsor, 29 August, 

 192s (L. B. W.). 



Suborder Anisoptera Selys 



The nymphs of the Anisoptera lack caudal tracheal gills but are 

 provided with rectal gills which supply the necessary oxygen to 

 the blood. They are much more robust than the nymphs of 

 Zygoptera. 



Adults of this suborder are larger in every way than the adults 

 of Zygoptera, their flight is much more rapid and certain, and they 

 rest without exception with wings spread horizontally. 



Key to Families 

 Nymphs 



1. Labium forming a more or less spoon-like mask for the ventral 



surface of the head ; the mentum never with two large teeth at 



the middle of the distal margin LIBELLULIDAE, p. 198 



Labium flat, not forming a spoon-like mask for the ventral part 

 of the head ; or if spoon-like, then the mentum produced triangu- 

 larly in front with two teeth at the middle of the distal margin 2 



2. Distal margin of the mentum cleft ; front and middle tarsi with 



three segments 3 



Distal margin of the mentum continuous ; front and middle tarsi 

 with two segments GOMPHIDAE, p. 124 



3. Labium spoon-like and covering the ventral and cephalic surfaces 



of the head up to the antennae; median lobe angularly pro- 

 duced with two teeth at the apex (Fig. 7, No. i) ; wing-cases 



of nymphs (not exuviae) strongly divergent 



CORDULEGASTERIDAE, p. 118 

 Labium not spoon-like or covering the ventral and cephalic sur- 

 faces of the head to the antennae ; median lobe not angularly 

 produced or with teeth at the apex ; wing-cases of nymphs not 

 strongly divergent 4 



4. Antenna! segments shorter than wide; mentum with a broad 



shallow cleft PETALURIDAE, p. 116 



Antenna! segments longer than wide ; mentum with a narrow cleft 

 usually reduced to a line AESHNIDAE, p. 169 



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