134 



THE YOUNG NATUKALIST. 



But we will suppose our specimen has a rather thin and slender abdomen. 

 We know then it must be referred to the family Libellulidse, but there are 

 over a dozen species belonging to this family ; how are we to decide which 

 it is ? Before I answer that question allow me to call your attention to the 

 wing of this dragonfly. You will notice there is a slight depression between 

 the middle of what, in a lepidopterous insect, we should call the costal mar- 

 gin, and the base of the wing, and just at this point you see there is a short 

 dark perpendicular line. Now, this particular part of the wing is called the 

 cubital point. All the way along what, in a butterfly, we should call the 

 costa are a series of short perpendicular nervures. Those which come 

 between the cubital point and the base of the wing are called the ante-cubital 

 nervures. Now, in five of the British species of Libellulidse, the ante-cubital 

 nervures are ten to sixteen in number, in the remaining eight species there 

 are not more than from six to eight. The species with from ten to sixteen 

 ante-cubital nervures are Libellula quadrimaculala, L. depressa, L.fulva, 

 L. cancellata, and L. ccerulescens. The first of these is generally distributed, 

 the others are more or less local. 



Libellula quadrimaculata has a body about an inch and four lines in length, 

 and the wings expand about two inches eight lines. The abdomen is brown, 

 rather broad and conical with a black tip. The wings all have a brown spot 

 in the middle of the costal margin, and there is also a brown patch of a 

 triangular shape at the base of the hind-wings. They each have a broad 

 abdomen ; the first named a very broad one much depressed. In both species 

 its colour is brown in the female, and powdered with cobalt-blue in the male. 

 Both species are exactly alike in size. The body is the same length as 

 L. quadrimac?ilata } viz., one inch and seven lines, and the expanse of wings 

 similar ; that is about two inches eight lines. In L. depressa the abdomen 

 is spotted with yellow. 



L. cancellata and L. ccerulescens both have clear wings. In the former 

 they expand the same size as the preceding mentioned species ; in the latter 

 they are half-inch less. They are thus easily distinguished from one another; 

 moreover, L. cancellata has the abdomen broad, in carulescens it is narrow, 

 flattened, and keeled in the middle. In both species it is covered with a 

 blue bloom in the male. The female is brown, and in L. cancellata there 

 are two longitudinal black bands, and in carulescens two longitudinal lighter 

 stripes. They are both local species, but the latter is the most widely dis- 

 tributed. 



All the species of Libellulidse with from six to eight ante-cubital nervures 

 have black legs, but in five of these, viz., L. flaveola, L. Fonscolombii, 

 S, meridionalis, L. striolata, and L. vulgata, the external part of the legs is 



