198 Mr. F. W. Bawa on British Limnobiidae. 
9. Apical antennal joints elongate, with long bristles (thorax 
yellowish with three dark stripes) , 2 aD: 
Apical antennal joints rounded or shortly vals with short 
bristles . : : : : j oe gh 
10. Discal cell open; ovipositor black at the = tine 
patens Lundst. 
aS Discal cell closed ; ovipositor all yellowish beneath . 10a. 
~ 10a, Antennae all black ; ; 4 ; ventralis Schum. 
Basal joint of antennae yellow : : -  modesta Mg. 
11. Cross-veins clouded (more or less); a dark spot at apex of Rs 
which extends obviously into the upper basal cell; legs very 
\ slender, the femora usually with distinct dark tips; abdominal 
segments pale posteriorly. ; ; : chorea Mg. 
Cross-veins not clouded, or only very indistinctly; apex of Rs 
without a dark spot, or with a very small one which does not 
extend into the basal cell; legs usually stouter, the tips of the 
femora less distinctly darkened; dorsum of abdomen nearly 
uniform in colour : : . 12. 
12. Thorax entirely yellow, w shank distinct grey Sanoane! basal 
joint of antennae usually yellow . : ; lutea Mg. 
Thorax dark, at least in the middle of the mesonotum, which 
usually has a distinct grey pollinosity . < ¢ Rede IX 
13. Black or dark grey species, with greyish pleurae ; . 14, 
Yellowish species, at least with yellowish pleurae _. ae hO. 
14. Stigma absent or very faint . ; ‘ ; , . l4a. 
Stigma distinct . : ; : : 5 : a aD. 
14a. Halteres extremely long (about as long as the greatest breadth 
of the wing), the whole knob and most of the stem dark 
halterella sp. n. 
Halteres much shorter, tip of knob only dark . sericala Mg. 
15. Wings perfectly clear, scarcely longer than the abdomen; 
stigma squarish, black; central stripe of mesonotum scarcely 
shining. . : . stigmatica Mg. 
Wings slightly nanan aaa Sees longer than the 
abdomen; stigma rather longer, brown to brownish-black ; 
mesonotum with shining blackish central stripe 
affinis Schum. 
16. Dorsum of abdomen mainly or entirely dark; thorax without 
N distinct stripes; cross-veins and base and apex of Rs often 
slightly infuscated =. ° : mitis Mg. 
Abdomen mainly yellow, at most w ith a ‘lachiat longitudinal 
stripe; three dark stripes on mesonotum ; cross-veins and Rs 
never infuscated : : : ; : F ieee bY 
