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the distal part is almost as long as the basal one, 
thin, linear. 4. P. spectabilis n. sp. 
b. llie haiis on the upper surface of the head are cylindrical. 
A thick median process projects from the hind margin of 
the stemum of the anal segment. The anal plate is incised 
in scarcely two thirds of the length from the base to the 
apex of the inner branches. 5. P. spinifer n. sp. 
B. The anal plate with two, four or six branches, and if four are 
piesent the inner pair is either rudimentary or situated in a 
considerably higher plane than the outer. The anterior ventral 
setæ on the anal segment are short and perhaps sometimes 
wanting. The last pair of legs is rarely rather long, generally 
rather short or very short. 
a. The anal plate has four well-developed branches situated in 
two planes. 
a. The teigum of the anal segment is produced backwards 
into an acute process; its setæ are exceedingly long. 
The last pair of tactile setæ is very long and robust 
with the pubescence very long. 
6 . P. cmnatus n. sp. 
/?. The tergum of the anal segment has no process, and its 
setæ are short. The last pair of tactile setæ are short 
thin, proximally naked and distally faintly pubescent. 
16. P. vulgaris n. sp. 
b. The anal plate has a comb of six branches in one plane. 
14. P. pectinatus n. sp. 
c. The anal plate has two branches, in three species ( P . gra- 
cilis, P. pygmæus and P. oculatus ) besides an inner rudi¬ 
mentary pair. 
a. The lower antennal branch with its anterior flagellum 
more than two thirds as long as the posterior one. 
t* The last segment of the trunk with its setæ long 
and robust. 8. P. inornatus n. sp. 
