Apterygote (primarily flightless) insects with entognathous mouth-parts, many segmented antennae, ten large abdominal segments followed by one small abdominal segment which carries the variably formed paired cerci. They have no eyes at all.
The Diplura or two pronged bristle-tails (from diplos = double and oura = a tail) are another group of soil and leaf-litter insects of ancient origin, they are mostly small (the largest being about 5cm long), often white in color and occur all over the world. There are around 800 known species 11 of which occur in Great Britain and 70 in North America. The cerci or (tails) are often long, but may be short and stubby or even pincer like.