386 
lateral setæ and often rather or considerably reraote from tliem; the 
lateral setæ, though generally longer than the other dorsal pairs, 
are never half and sometimes not one third as long as the breadth 
of the segment; the posterior pair of ventral setæ is from twice to 
ahout four times as long as the lateral dorsal pair. The styli are 
generally somewhat longer than in the species 7—11; the anal 
plate is rarely rounded posteriorly, and the number of the branches 
varies from two to six. The sternum of the anal segment has at 
least two pairs of setæ, but it was often impossible to discover 
an anterior pair. The legs are rnoderately to very short. 
13. P aur opus siamensis n. sp. 
PI. IV, fig. 3 a—8 f. 
Material. An adult and well-preserved male. 
Head (lig. 3 a). The eyes are of middle size and somewhat more 
than twice as long as broad; the distance between them is some¬ 
what shorter than their length. — The liairs are all thin and cy- 
lindrical; those in the lirst and the third row and the submedian 
j)air in the fourth row are moderately short, those in the second 
row are proportionately long and subequal in length; the interme- 
diate and sublateral pairs are equal in length, only as long as those 
in the second row and half as long as the eyes. 
Antennæ (fig. 3 a). The upper one of the front hairs on the 
fourth joint is slightly longer than the two distal joints together 
and a little longer than the other hair. The upper branch is four 
times longer than broad and somewhat shorter than the two distal 
joints together; the flagellum is two and a half times longer than 
the branch and only about two thirds as long as the breadth of 
the head. The lower branch is rather little shorter than the upper, 
twice as long as broad, widening somewhat from the base outwards, 
and the anterior angle is only a little more obliquely cut off than 
the posterior one. The posterior flagellum is only a little shorter 
than that of the upper branch and slightly longer than the anterior 
flagellum. All three flagella are rather siender, cylindrical, and 
