352 
ff. The last segment of the trunk with its setæ short 
and thin. 
§. Most of the hairs on the upper surface of the 
head are conspicuously clavate. The styli are 
siender, cylindrical; the anal plate posteriorly 
with a rather deep median incision. 
15. P. helveticus n. sp. 
§§. The hairs on the upper surface of the head are 
thin, cylindrical. The styli are exceedingly club- 
shaped; the anal plate has two thin branches 
rather near each other. 
13. P. siamensis n. sp. 
ft. The lower antennal branch with its anterior flagellum 
not half as long as the posterior one. 
f. The anal plate is posteriorly rather broadly rounded, 
with its two branches projecting from the hind mar¬ 
gin as cylindrical processes not far from each other, 
and with no lobe of the plate between them. 
§. The upper antennal branch is considerably or much 
longer than the lower. The distance between the 
eyes slightly or not shorter than their length. 
□ . All the hairs on the upper surface of the 
head are thin, cylindrical. The flagellum 
of the upper antennal branch is longer than 
the breadth of the head. 
10. P. elegantulus n. sp. 
□ At least raany of the hairs on the upper 
surface of the head are very conspicuously 
clavate. The flagellum of the upper an¬ 
tennal branch is shorter than the breadth 
of the head. 
x. The branches of the anal plate are 
several times longer than their di- 
