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stiges of a pair of limbs; in the two posterior segments legs are 
totally wanting, and each of the others has one pair. In all forms 
the two anterior segments are united beneath one dorsal plate (or 
one pair of dorsal plates); the eight following segments have four 
terga — each tergum covering two segments — in two of the fa- 
milies, while in Brachypauropodidæ eight pairs of plates are more 
ér less separated from each other (see below in the description of 
this family). Each of the two posterior segments has a tergum of - 
its own. ; 
In the descriptions I have divided the body into two portions: 
. the trunk and the anal segment, the latter presenting many fea- 
tures not met with in any of the other segments. 
Tactile Setæ. All authors have described the five pairs of long 
tactile setæ found in all adult animals; nevertheless, these setæ 
have not been studied sufficiently. AN setæ in all species seen by 
me are pubescent in at least the distal third, and generally only a 
shorter basal part of them is quite naked. But the pubescence is 
very different: sometimes it is very short and so delicate that it 
can only be perceived under rather high magnifving power (400 to 
600 times), sometimes it is conspicuous by a very low degree of 
enlargement. The fine branches are often oblique, sometimes they 
are vertical on the seta. In all genera and species the setæ can 
be referred to three groups: the two anterior pairs are always very 
much alike in the same species; the two posterior pairs are at 
least rather similar in structure in the same form, while the last 
of them is often somewhat or considerably longer and thicker than 
the fourth pair; the third pair is sometimes not very different from 
the fourth, but often it shows a structure of its own and is more 
or less thickened at the middle or at the distal end, while the 
other four pairs are always regularly tapering almost from the base 
to the end. Furthermore, the setæ of the two anterior pairs aré 
rather similar in all species, thin, and adorned with a conspi- 
cuous, yet very delicate and moderately short pubescence. The sete 
of the two other groups are very different in various species and 
