414 NEUROPTERA 



Several peculiarities in the internal anatomy deserve notice. 

 The alimentary canal in Libellula, is about as long as the body, 

 the oesophagus and chylific stomach being elongate, while the 

 intestine is short and divided into only two parts ; there is no 

 definite proventriculus. The Malpighian tubules are shorter 

 than usual ; they are about forty in number. The male has no 

 vesiculae seminales ; the vasa deferentia are elongate, and the 

 ejaculatory duct is very short, being in fact merely a common 

 sinus formed by the terminations of the vasa deferentia. The 

 opening of this duct is situated on the penultimate ventral plate ; 

 the organs of intromission are, however, placed much anterior 

 to this, on the under side of the second segment. The mode in 

 which the fertilising fluid is transferred from the ninth to the 

 second segment is not well understood, but it is known that 

 the abdomen is flexed by the Insect so as to bring the ninth 

 ventral plate into contact with the second. The three thoracic 

 ganglia of the nervous chain are all contiguous, though not 

 completely amalgamated ; the abdominal ganglia are seven in 

 number, and are all separated, the terminal one being larger than 

 the others. Dufour, after repeated dissections, was unable to find 

 any salivary glands, but Olga Poletajewa x states that they exist. 



The Odonata must be ranked among the most highly- 

 organised Insects so far as external structure and powers of 

 locomotion are concerned ; the peculiar modifications of the 

 thoracic segments and the relative positions of the wings and 

 legs mark a great departure from the normal type of Insect 

 structure. Their prey consists of living Insects, which they cap- 

 ture on the wing by their own superior powers of flight. They 

 destroy a great many Insects, their appetite for food being, as in 

 the cases of the Mantidae and of the tiger -bee ties, apparently 

 almost insatiable. They are admirably constructed for the pur- 

 poses of their predatory lives ; they fly with great swiftness and 

 change the direction of their flight with admirable facility. 

 They are, however, dependent 011 sunshine, and conceal them- 

 selves in dull and cloudy weather. The larger Insects of the 

 family belong to the division Anisopterides (Fig. 260, Anax 

 formosus), and some of these may, in our own country, usually be 

 seen, in the bright sunshine of the summer and autumn, engaged 

 in hawking in their favourite haunts. Places where other Insects 



1 Horae Soc. ent. fioss. xvi. 1881, p. 3. 



