No. 39] ODONATA OF CONNECTICUT: LIBELLULIDAE 269 



Lateral spines of segment 8 more than twice, those of 9 three times 

 as long as basal breadth, outer margins of latter nearly straight, 

 lateral appendages less than half as long as the inferiors, the 

 latter apically acuminate vicinum 



4. Dorsal hooks well developed, slender and very acute, that of seg- 



ment 7 nearly as long as the mid-dorsal line of the segment, 



that of 8 usually more than half as long as the segment 5 



Dorsal hooks smaller and when well developed somewhat stouter 

 and distinctly curved, that of segment 9 distinctly shorter than 

 the segment, that of 8 rarely half as long as the segment 6 



5. Base of mentum of labium distinctly broader than the distance 



between middle coxae and somewhat more than one-fourth the 

 greatest width ; lateral spines of segment 9 usually at least half as 

 long as lateral margins of the segments ; lateral setae typically 11 



(costiferum) 

 Base of mentum of labium scarcely, if at all, broader than middle 

 coxae and about one-fourth of the greatest width, lateral spines 

 of segment 9 two-fifths to one-half as long as lateral margins 

 of the segment ; lateral setae typically 10 (pallipes) 



6. Dorsal hooks present on segments 4 to 7 or 8, sometimes absent 



from segment 4 or 8, lateral spines of segment 9 about one-third 

 as long as the lateral margins of the segment, lateral setae 9 



to II 7 



Dorsal hooks present on segments 5 to 7 only, vestigial, or absent 

 altogether, lateral spines of segment 9 about one-fifth as long as 



lateral margins of the segment, lateral setae usually 11 



rubicundulum decisum 



7. Lateral setae 11, dorsal hooks vestigial or absent from segments 



4 and 8 danae 



Lateral setae 9 or 10, dorsal hooks somewhat larger, generally 

 present, though small on segments 4 and 8 obtrusum 



8. Lateral setae 9, mental setae about 13, 7 in the stronger, outer series 



(illotum) 

 Lateral setae 13 to 14, mental setae about 17, 9 in the outer series 



corruptum 



Adults, Males 



1. Fourth abdominal terga with a transverse carina at middle corruptum 

 Fourth abdominal terga without a transverse carina at middle ... 2 



2. Sides of thorax marked with bright yellow danae 



Sides of thorax not marked with bright yellow ; brown or red . . 3 



3. Superior anal appendages with a sharply angled ventral tooth near 



the middle ; hamules not divided proximad of the middle 4 



Superior anal appendages without a sharply angled ventral tooth 

 near the middle ; hamules divided far proximad of the middle . . 6 



4. Legs black with exception of the ventral side of the front femora 5 

 Legs pale yellowish with black spines ambiguum 



5. Hamules with a deep notch (Fig. 67, No. 4) rubicundulum 



Hamules with a shallow notch (Fig. 67, No. 3) obtrusum 



6. Hind wings chlorinated from base to nodus ; front wings from 



bases to triangles, PI. xxii, a semicinctum 



Hind wings not chlorinated from base to nodus nor the front wings 

 from bases to triangles 7 



7. Legs light brown to brownish red; stigma small (2 mm. long).. 



vicinum 

 Legs dark brown to black ; stigma 3 mm. in length (costiferum) 



