120 Mr. Curtis's Descriptions of some nondescript 



ceedingly faint bands of red and green light perpendicular to 

 the direction of the motion. 



When the eye has not been fatigued by light, the luminous 

 ground on which these phaenomena are seen has a minutely 

 granular appearance; and by the continued action of the light 

 an apparent effervescence appears over the whole, as if each 

 grain of light, or the minute spaces between the grains, were 

 becoming more or less luminous in succession. 



Belleville, Dec. 18, 1833. 



XXVI. Descriptions of some nondescript British Species of 

 May-flies of Anglers. ByJoms Curtis, Esq., F.L.S.,Src* 



AS few insects are more remarkable in their ceconomy or 

 • more employed for the amusement of men than the Ephe- 

 merae and Phryganidce, I hope the characters of some new 

 genera and species may induce others to pay attention to these 

 curious and interesting tribes of insects. 



The following descriptions are scarcely more than the es- 

 sential characters: the numbers refer to Mr. Curtis's Guide 

 to an Arrangement of British Insects, in which a list of the 

 species has been given. 



Order NEUROPTERA. Fam. Ephemerid*. 

 Gen. 734. Ephemera Linn. 

 7. fusca Curt. 

 2\ lines long : dull piceous, the space between the eyes and the base of the 

 anterior legs ferruginous, the others ochreous ; filaments longer than the 

 insect, pale lurid, dotted ; the articulations long : wings transparent, supe- 

 rior with few transverse nervures and the longitudinal ones most distinct ; 

 inferior very small. 



Gen. 735. Baetis Lea. 

 A. The wings very much reticulated. 



2. dispar Curt. Brit. Ent. pi. 484. 

 The Pseudimagof of this insect may be the E. venosa DeGeer. 



7. costalis Curt. 

 5 lines long : slender, pale castaneous, sides of thorax, apex of abdomen 

 and legs ochreous, the joints of tarsi fuscous at the articulations ; filaments 

 very long, pale yellow, each joint with the apex black : superior wings 

 with the costa brownish yellow. 



6. elegans Curt. 

 4Jr lines : bright ochre, abdomen inclining to pale chestnut ; filaments whitish 

 dotted with fuscous, tarsi with all the joints tipped with black : wings beau- 

 tifully opalescent, stained very pale yellowish brown, the costa darker, espe- 

 cially towards the apex. 



* Communicated by the Author. 



t By Pseudimago I designate the fourth state of the Ephemeridce. 



