1S52] 
Bellinger — Isotomidae 
21 
are distributed as follows : one on each side of each thoracic 
tergite; one on the base of the prothoracic leg; two to five 
on the bases of the mesothoracic and metathoracic legs; 
two or more pairs on each abdominal tergite, becoming 
more numerous posteriorly. These setae (fig. 6) bear a 
small number of strong, well spaced teeth. 
The characteristic vestiture of the fused fifth and sixth 
abdominal segments is as follows (fig. 8) : mixed simple 
and serrate setae in a line at the anterior border of the 
tergite, and at the sides posteriorly; dorsally, behind this 
line, a straight transverse row of eight long, straight, 
simple, blunt-tipped setae (fig. 7) ; behind this row five 
similar setae in a W-shaped line, two anterior and three 
posterior ; along the posterior margin a straight row of five 
long, straight, simple, sharp-pointed setae. Among the 
first two rows are scattered a number of very fine hairs ; 
two additional fine hairs, of which the anterior is minute, 
are just inside and in front of each of the two lateral blunt 
setae of the third row. On each side of the tergite, in the 
first row, is a short, broad sensory hair. 
Antenna slightly longer than head; relative length of 
segments (expanded) 2:3:3:6. Fourth segment (fig. 1) 
enlarged, oval, ending in a blunt cone; dorsally with a 
number of blunt, cylindrical sensory hairs. Sense organ of 
third antennal segment with two short, curved rods directed 
anteromediad, and two adjacent guard hairs, the ventral 
one straight, the dorsal curved and somewhat posterior to 
the rods. 
Postantennal organ (figs. 2, 3) longer than the greatest 
width of the second antennal segment (about 5:4), broadly 
oval with a border about Vb of its greatest diameter in 
width; this border is interrupted at each end, and midway 
on each side, by fine partitions. Eyes absent. 
Unguis (fig. 4) moderate in length, curved, untoothed. 
Empodial appendage three-winged, more or less triangular 
with acuminate apex; about i /2 length of unguis. Tenent 
hairs absent. Tibiotarsus with an incomplete distal sub- 
segment; the suture is evident only ventrally. 
