364 
the length of the two outer pairs of hairs in the fourth row: the 
intermediate setæ are exceedingly long, much longer than the eyes, 
almost as long as the distance between them and twice as long as 
the sublateral setæ. 
Antennæ (fig. 4 a). The two front hairs on the fourth joint 
are slightly longer than in P. intermedius. The upper branch is 
about eight times longer than broad and a little longer than the 
peduncle; its flagellum a little more than twice as long as the 
branch. The lower branch is longer than that in the three prece- 
ding species and about four times longer than broad, its anterior 
distal angle is considerably more obliquely and deeply cut off than 
the posterior; the posterior flagellum is one fifth longer than the 
anterior; all three flagella are very siender. The globulus is small, 
its transverse diameter conspicuously shorter than that of the upper 
branch; the stalk is rather short. 
Trunk. Robust. — The three posterior pairs of tactile setæ 
and espeeially the third and the fourth pairs are proximally thicker 
than in P. Huxleyi ; the fifth pair is nearly three times longer 
than the breadth of its segment; the fourth pair is more than three 
fifths and the third pair scarcely half as long as the fifth pair; 
all are tapering and shortly pubescent almost to the base. — The 
dorsal setæ on the penultimate and the last segments (hg. 4 b) are 
slightly tapering, very tliick and exceedingly long, longer and thicker 
than in the three preceding species. 
Anal Segment (fig. 4 b). The tergum is produced backwards 
into a rather small triangular projection; its three pairs of setæ 
are very thick, acute, proportionately short, the two outer pairs 
being a little more than one fourth of the longest setæ on the 
last segment of the trunk, and the submedian pair a little shorter 
than the sublateral setæ. — The styli are about as thick as in 
P. intermedius and somewhat longer than in that species. — The 
sternum has its posterior setæ somewhat shorter than the dorsal 
setæ on the last segment of the trunk. — The anal plate (fig. 4 c) 
with the proximal portion of the inner branches shaped like a very 
