The second sub-family, the Cordulidæ, contains four British species, of which the beautiful Cordulia metallica is the typical example.
The Æschnidæ contain some of the largest members found. The great dragon fly (Æschna grandis) is one of these. It is nearly three inches long and four inches in expanse of the wings, and is of a light rusty-brown colour with a few pale markings.
Of the Gomphidæ only four species inhabit our own country.
Gomphus vulgatissimus is a black insect, nearly two inches long, with yellow bands on the thorax, and a line of the same colour along the back of the abdomen.
Family 2, Agroninæ.—This family contains a number of slender-bodied insects. There are two sub-families.
The Agrionidæ are a very numerous group. The typical form, Agrion puella, which is a beautiful, slender creature, measures about two or two and a half inches in expanse of the wings. The abdomen of the male is banded with azure blue, that of the female being brassy-black.
The Calopterygidæ contain only two British species—viz., Calopteryx virgo and C. splendens.
Fig. 55.—Calopteryx Virgo (Male).