TACHIDIUS. et 
with rather long hairs, some of which are plumed with 
strong spine-like setz; in the male the fifth and sixth 
joints form a large vesiculiform swelling (fig. 3), the 
last joint forming a strong claw; a curved spine is 
also attached to the outer margin of the swollen joint 
(fig. 3a). Posterior antenne 2-jointed, the secondary 
branch (fig. 5) small, 1-jointed. In the male the 
inner branch of the second pair of feet (fig. 11) has its 
marginal setz much reduced in size, and the second 
joint has attached to its apex a strong spine which is 
nearly as broad and quite as long as the much nar- 
rowed terminal joint; the outer branch of the third pair 
has also very small marginal seta and is armed at its 
extremity with three strong spines (fig. 12), one of 
which is very long. Fifth pair of feet in both sexes 
broad, subquadrate, single-jointed, much larger in the 
female (fig. 13) than in the male (fig. 14), and bearing 
several marginal setz, some of which are plumose. 
The innermost of the two principal tail sete is much 
the longest, and both are finely aculeate throughout 
(fig. 16). The first abdominal segment bears on its 
outer angles (fig. 15) two spines. Hye small, situated 
near the base of the anterior antenna. Colour grey 
or yellowish brown. Length 7th of an inch (‘65 mm.). 
There are probably few brackish marsh-pools in 
which Tachidius brevicornis may not at times be found, 
more especially in the autumn months, when long- 
continued warmth has developed many successive ~ 
broods of these rapidly multiplying tribes. In pools 
of this kind I have found it often in great abundance, 
the following being some of the localities of which I 
