272 



NEW YORK STATE MUSEUM 



Abdomen with a pair of broad, dorsal fuscous stripes inter- 

 rupted on the sutures, extending posteriorly to end at the bases 

 of the lateral appendages on each side, including a pair of trans- 

 versely placed darker spots [fig.l6]. On each side, half way 

 from this band to the lateral margin, there are on each segment 

 a pair of brownish marks, of which the lower one is transversely 

 placed and rests on the apical carina of the segment; each lateral 

 appendage is black on its lateral margins. 



No dorsal hooks at all. Lateral spines almost wanting, repre- 

 sented on\j on the ninth segment by a very minute tooth, which 



Fig. 17 Labium ofSympetrum corruptum 



continues the inward slope of the lateral margin. Sides of 

 abdomen nearly parallel on segments 4-7, slightly narrowed 

 posteriorly on 8, strongly narrowed on 9; 10 annular, included, 

 one fourth to one third as long as 9; superior appendages aa 

 long as segments 9 and 10 together, lateral appendages fully one 

 third shorter than the others; the lateral and ventral margins 

 of segments 9 and 10 yqvj hairy. 



This species differs from its nearest relative, S. i 1 1 o t u m, 

 (1) in having 13-14 lateral setae on its labium [see flg.l7], in 

 S. illotum there are but 9; (2) in having about 17 mental 

 setae, each side of which there are nine in the stronger outer 

 series — in illotum there are about 13, and seven in the 

 stronger outer rank; (3) in having the lateral spines even less 

 developed; (4) in having a better developed color pattern. Ex- 

 cept in these particulars the nymph of S. illotum (of which 



