AMERICAN ODONATA. 



207 



1. Abdominal segment 8 longer than 9.* % .—Segments 7-9 greatly dilated ; 



second hamule forked. 9-— Vulvar lamina not shorter than one- 

 seventh the sternum of 9 2. 



Abdominal segment 8 shorter than 9.* '^.—Segments 7-9 slightly dilated; 

 second hamule simple. ? .—Vulvar lamina shorter than one-seventh 

 the sternum of 9 • • -3. 



2. Segments 3-7 with a maculose longitudinal mid-dorsal stripe. . .amiiieola. 

 Segments 3-7 basally annulate with yellow scudderi. 



3. Abdomen black, marked with yellow or green ^■ 



Abdomen yellowish brown, marked with yellow or green; labrum largely 



green, no distinct markings plagiatiis. 



4. Abdominal segments 7 and 9 about equal in length ; labrum with the margins 



and a more or less distinct central spot, yellowish spiuiceps. 



Abdominal segment 9 shorter than 7; labrum with the margins and a longitudi- 

 nal median stripe (rarely reduced to a central spot), black. .iiotal US. 



In listing the material examined of each species, mention is made 

 of tho.se persons and institutions to whom my thanks are due for the 

 loan of specimens. At the Acad. Nat. Sci., Phil., I am indebted to 

 Dr. Calvert ; at the U. S. Nat. Mus., to Mr. Currie ; at the M. C. 

 Z., to Mr. Henshaw ; and at Ohio State University, to Mr. Hine. 

 Measurements, descriptions and notes given under each species have 

 been made from material examined by myself, unless otherwise 

 stated, and have no reference to hitherto published accounts of 

 these species. 



1. GoinphuN amnicola Walsh., Proc. Acad. Phil., p. 396, 1862. 



Ab. -^35; 9 35-36; H. w. % 29-31; 9 33. 



Antecub. f. w. 11-14; h. w. 7-11. 



Postcub. f. w. 7-12 ; h. w. 8-12. 

 Face yellowish, labrum margined with black, rarely an indistinct median spot 

 of same color ; anteclypeus dark or pale ; lower lateral edges of postclypeus moie 

 or less black, usually the lateral depressions also dark ; suture between frons and 

 clypeus, and frons above at base, black. Mesothoracic half-collar not interrupted, 

 continuous with the pale area of the mid-dorsal carina, which includes the carina 

 itself and usually a little on either side; dorsal stripes isolated, strongly conver- 

 gent above, in one specimen continuous above with the pale of the mid-dorsal 

 carina area; antehumeral pale stripe interrupted above and rarely also at other 

 points; humeral and first lateral suture each with a black stripe, the latter inter- 

 rupted above or more rarely complete. Abdomen with a maculose longitudinal 

 mid-dorsal stripe. Legs black, first femora brown beneath, and last femora ])ale 

 dorsally ; in tenerals all the femora are pale and the tibijB and tarsi brown. 



'^ .— Accessory genitalia of 2 black ; sides of 8 and 9 each with a large yellow 

 blotch ; 10 and appendages black or very dark. 



9. —Abdominal segments laterally conspicuously marked with yellow; 8 and 

 9 scarcely dilated ; vulvar lamina in length one-fourth to one-fifth sternnni of 9. 



* A character by no means always clearly evident in dried specimens ; excepting 

 for spiniceps, it may be generally said in this group tliat 8 and 9 are about equal. 



TRANS. \M. ENT. SOC, XXVII. MAY, 1901 



