1891-92-] Dragon-Flies : their Life- History. 9 



The internal structure of the dragon-fly is comparatively 

 simple. The whole digestive apparatus consists of a canal 

 extending from mouth to anus, comprising the gullet, stomach, 

 and intestine, with some dilatations and constrictions. Placed 

 round the posterior extremity of the stomach there are the 

 Malpighian bodies, stated to number about forty. There 

 appear to be no salivary glands. 



Flight in the largest species is bold and rapid, and quite 

 in keeping with their carnivorous instincts. In proportion 

 to their size it is much more powerful than that of birds. 

 The wings are four in number, and act similarly and simul- 

 taneously, in some species always expanded when at rest, in 

 others folded up or laid together. They are long, compara- 

 tively narrow, equal in size or nearly so, very thin, gauze- 

 like, and much reticulated, resembling the finest lace or net- 

 work, this latter condition being the result of the interlacing of 

 the numerous nervures which support the double membrane. 

 Under the microscope they are seen to have a double row of 

 tooth-like projections, giving them a serrated appearance round 

 their edges, the nervures also being armed with minute spines. 

 At the outer extremity, in most species, there is a curious 

 dense patch termed the " pterostigma," but whether formed 

 of nervous matter or for what use is not at present known. 

 It forms an aid, however, in classification. Most species can 

 remain for hours on the wing, when in pursuit of their prey, 

 their speed being such, it has been said, as to elude chase by 

 a swallow. As a proof of their staying power on the wing, 

 a case has been cited where a dragon-fly flew on board a ship 

 off the coast of Africa, the nearest land being 500 miles 

 distant. The specimen shown, Aeschna cyanea, was caught on 

 board the steamship City of Paris three miles off Sandy 

 Hook, on one of her voyages from New York this last sum- 

 mer. They are noted for their easy and rapid evolutions, 

 and are said to possess the remarkable power of flying in all 

 directions if necessary without turning. This statement, 

 however, after repeated watching, I have been unable to verify 

 for myself. 



Dragon-flies are possessed of six legs jointed to the under 

 surface of the thorax, in three pairs close together. They 

 are all alike in structure, and are directed forwards. When 



