206 Mr. R. MacLachlan's Monograph of 



Head yellowish ; vertex with a depression in the centre, 

 the raised portion with a broad black margin, which is 

 prolonged between the antennae, and connected with a 

 transverse line margining the posterior edge ; front with 

 a A -shaped black mark, the apex of which joins the 

 vertical mark between the antennas, a black spot on the 

 genge below the eyes, and a black line on each side of the 

 clypeus ; palpi black, pale at the articulations ; antennce 

 shorter than the wings, brown, the basal joint yellowish, 

 the second joint black. 



Prothorax above, with two somewhat quadrate black 

 spots on each side ; insertion of the coxae ringed with 

 black ; vieso- and meta- thorax strongly marked with 

 black on the sides, and lined with black beneath. 



Abdomen black, more or less varied with blue-green, 

 and with pale pubescence. The extent of black and 

 green varies in the sexes, and also in individuals inde- 

 pendently of sex. 



Legs green, with short black hairs ; tarsi brownish ; 

 imgiies dilated at the base internally. 



Wings short and broad, obtuse ; longitudinal veins 

 green, transverse veinlets all black and strong, ciliated 

 with black ; pterostigma darker. 



Nearly loses its bluish tint after death. 



Length of body 4-6 lines; expanse of wings 12-14 

 lines. 



Very common, especially in woods, throughout the 

 summer. 



It is to me a matter of doubt whether Linnets descrip- 

 tion of Henierohius chrysops does not refer to this insect 

 rather than his description of perJa, but Schaffer's figure 

 (Icon. Insect. Ratisb. pi. v. fig. 7-8), quoted by him, 

 well represents our perla. 



Hagen, in the '' Entomologist's Annual " for 1858, 

 p. 22, introduces, doubtfully, G. tenella, of Schneider 

 (Mon. Chrys. 94, pi. xxv.), on the authority of a speci- 

 men in the British Museum. Among some old doubtful 

 specimens there, I cannot find one that agrees with 

 Schneider's description of tenella, or with a continental 

 example so named for me by Herr Brauer. It may, 

 however, be assumed as certain that we possess more 

 species than are here described. 



