228 [October, 



PSORA GRACILIS, A NEW SPECIES BELONGING TO BECKER'S 



GROUP I. 



BY JOUN H. WOOD, M.B, 



This very distinct species, of which jxt present only the female 

 has been obtained, will come next to unispinosa, Ztt., with which it 

 agrees in having but two scutellar bristles and in the incrassated 

 second thick vein of the female. It is a particularly long and slender 

 insect, hence its name. 



9 . Thorax and abdomen black, tlie former shining and narrow, tlie latter dull, 

 long and slender ; frons highly glossy and scarcely broader than long, palpi black 

 and of the usual form ; wings dark gi'ey, especially in the course of the thin veins 

 which stand out conspicuously, costa barely to middle of wing, otherwise venation 

 and fringe as in unispinosa ; legs long and slender, dark brown or blackish, knees 

 yellow and front coxse pale yellow, a single small spine in upper third of middle 

 tibia; and a still smaller one at the tip on the outer side, none on fore and hind tibioe. 



Long., 2-2i ram. 

 The only species with which it can possibly be confounded is 

 unispinosa ; but at the same time the ])oints of distinction are many 

 and obvious, such as the narrow and glossy frons, the black palpi (iti 

 unispinosa they are of a clear )'ellow), the dark wings, and the colour 

 and armature of the legs. Pour examples have been taken, always 

 in late autumn, from September to November, in the years 1905, 6 

 and 7. Three were obtained by sweeping under high trees in Stoke 

 Wood, and the fourth was boxed whilst running up a beech trunk in 

 the park adjoining. 



The following alterations will be necessary in the table (vol. xvii, 

 p. 193):- 



19. — Halteres black or blackish. 



a. Legs moderately stout and yellow ; spines on all the tibioe... 



unispinosa, Ztt. 



b. Legs long and slender, dark brown ; no spines on fore and hind tibia;.. . 



gracilis, n. sp. 

 20. — Halteres whitish {nudipalpis), or yellow (autumnalis). 



As the question of distribution is always of some interest, 1 may 

 mention that since the publication of my former notes on the subject 

 two out of the four British species, which had not then occurred in 

 Herefordshire, have now turned up in the county, and in my own 

 home district too. They are carinifrons and femorata. The former 

 seems not uncommon in the autumn, and is usually found in wet 

 places ; but the latter is scarce, four only having been taken, the 

 dates ranging from April 24th to July 7th. 



Tarrington, Hereford : 



September, 1907. 



