THYSANURA . 
83 
cavity of the head, and also on account of the small size of 
the insects. Figure 89 represents them in place in the 
head, and also each separately. 
In certain respects these insects represent a connecting- 
link between the other six-footed insects (Hexapoda) and 
the Myriapods; for many of the Thysanura have rudiments 
of legs on the abdomen. It is believed, therefore, that they 
are much like the first insects that appeared on the earth 
in ancient geological times. 
The Thysanura undergo no metamorphosis, the young 
resembling the adult in form. 
The name of the order is from two Greek words: 
thysanos , a tassel; and oura , the tail. 
The Thysanura include two distinct types of insects; 
these are classed as suborders, and can be distinguished by 
the following table: 
TABLE OF THE SUBORDERS OF THE THYSANURA. 
A. With bristle-like and many-jointed appendages at the caudal end 
of the body (in a single genus these appendages are in the form of 
forceps, Fig. 91), and without a sucker on the ventral side of the 
abdomen, p. 83. Cinura. 
A A. With a forked sucker on the ventral side of the first abdominal 
segment. Abdomen with a springing apparatus near its caudal 
end, or without appendages, p. 84. Collembola. 
Suborder CiNURA (Ci-nu'ra). 
The Bristle-tails . 
Often the careful housekeeper sees in the ironing-basket, 
or upon the book-shelf where she is dusting, a flash of light 
like a tiny thread of quicksilver, that usually vanishes as soon 
as seen. 
If she is experienced she knows that this streak of light is 
a little animal, half an inch long, whose body is clothed in 
shining scales like those of a fish. Hence she calls it a Fish- 
moth. Its scientific name is Lepisma saccharina; (Le-pis'ma 
sac-cha-ri'na); it is especially abundant in warm climates, 
