XVIII] 



BRITISH SPECIES 



349 



37. A. mercuriale Charpentier. $ abd 21 26, hw 15 19, pt 0-5. More 

 robust than No. 36. Abd. 1 3 as in fig. 179, d; app. inf. small. $ abd 21 27, 

 hw 15 19, pt 0-5; closely resembles No. 36, but abd. stouter, pt shorter ; blue 

 replaced by greenish. Rare ; New Forest. May Aug. 



38. A. puella Linn. abd 24 29, hw 17 20, pt 0-7. Very slender 

 species, of larger size than Nos. 36, 37. Abd. 1 3 as in fig. 179, e. $ abd 

 23 29, hw 18 23, pt 0-8 ; abd slender, seg. 2 with black mark along its whole 

 length; blue replaced by green, blue-green or yellowish. Very common; 

 May Sept. 



Genus XVIII. Erythromma Charpentier. Venation as in XVII. No 

 postocular spots. No ventral spine under seg. 8 in $. Coloration of o 

 bronze -black and pale blue. Eyes reddish in ,$, golden- brown in <j>. 



a. b. c. .d. e. f. 



Fig. 179. Colour-pattern (bright blue and bronze-black) of first three abdominal 

 segments in the males of Agrion and Enallagma. a, Agrion armatum Charp. ; 

 b, A. pulchellum Vand.; c, A. Jiastulatum Charp.; d, A. mercuriale Charp.; 

 e, A. puella Linn. ; /, Enallagma cyathigerum Charp. After Ris. 



39. E. naias Hansemann. $ abd 25 28, hw 20 24, pt 0-9. Thorax 

 black above, without dorsal stripes. Abd. pale blue on 1, sides of 2, and all 

 9 10. App. sup. stout. $ abd 26 29, hw 22 25,ptO-9; thorax with two 

 yellow dorsal lines; abd. 1 yellow with a black spot; rest bronze-black, 

 sutures 2 6 yellow, 7 9 blue. Local; Southern. May July. 



Genus XIX. Pyrrhosoma Charpentier. Characters as in XVIII, but abd. 

 red, or red and black. 



40. P. nymphula Siilzer ( =P. minium Harris). <$abd26 30, hw 21 23, 

 pt 0-9. Robust species. Thorax black with narrow red bands. Abd. bright 

 red, 7 black, 89 partly black. 9 abd 2529, hw 2225, pt 1 ; abd. stouter, 

 with duller red and more black. Very common. Apr. Aug. 



41. P. tenellum de Villers. <$ abd 2225, hw 1518, pt 0-5. Very 

 slender species. Thorax dark bronze; abd. wholly red. $ abd 25 28, hw 

 17 20,^0-6; thorax darker ; abd. I 3 red, 4 10 bronze-black. Common; 

 Southern. June July. 



Tribe Pseudagrionini (Characters, p. 280). 



Genus XX. Enallagma Selys. Characters as in XVII (except for position 

 of Ac, a tribal character). 



42. E. cyathigerum Charpentier. <J abd 25 28, hw 18 21, pt 0-7, black. 

 Abd. blue, with black pattern of 1 3 as in fig. 179, /, 6 7 considerably blacker, 



