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Ninth abdominal segment. 
Instead of being transverse, and as short as, or shorter than the 
proceeding segments as is the rule in other Zubulifera, the ninth 
abdominal segment is very distinctly elongated and longer than the 
preceding. We have had the opportunity of examining the larval 
forms of several Tubulifera, and it is interesting to note that in 
each case the ninth segment is elongated and much longer than the 
preceding; it seems quite possible that a study of the Thysano- 
pterous larva will prove very helpful. 
Secondary sex characters. 
Well-marked secondary sex characters appear to be exceptional 
in the Zhysanoptera; in the Tubulifera the male is generally 
smaller, and has the abdomen more slender, whilst the thorax is 
sometimes bigger and more convex; the forelegs are almost always 
bigger and more or less strongly incrassate, and the fore-tarsus is 
armed with a stouter tooth. 
There are however exceptions, such as the genus Dinothrips 
BAGNALL, wherein the male (but not the female) is armed with a 
pair of bifurcate mesosternal projections and a strong tubercle on 
the inner side of each intermediate femur. 
Urothrips possesses secondary sex characters of distinct import- 
ance. 
Maxillary and labial paipi. 
These are only single-jointed in Urothrips, but in all other 
species of Tubulifera they are distinctly two-jointed. 
In the Zeredrantia the joints in the palpi vary as follows : 
Thripide : Maxillary palpi 2- or 3-segmented, and the labial 
palpi always 2-segmented. 
Æolothripidæ : Maxillary palpi geniculate, 3- to 7-segmented, 
and the labial palpi 2-, 4- or 5-segmented. 
