OF THE UNITED STATES 



43 



drinkers of water, and feel the loss of that fluid very severely; 

 this can be easily tested by depriving one of it, and then placing 

 some within its reach. The insect will plump up imediately after 

 it has had a good draught. 



In concluding this brief account I must tell you that a great 

 many fossil spiders have been found, even as far back as the coal 

 formation. Some of the very best of these have been preserved 

 in amber, which, as has been stated, is but a fossilized resinous 

 germ of the ancestors of our coniferous trees. Even now, this 

 process can be easily studied in any pine forest, for spiders still 

 continue, as of old, to run up and down such trees, and when 

 they become entangled in the clear exuding gum, they often be- 

 come completely embalmed in time by the same material flooding 

 over them. Time and fossilation does the rest. 



Let us now consider some other group of this division of inver- 

 tebrate forms, and it may be remarked that books and papers to 

 the extent of a small library have been published upon those 

 truly remarkable insects known as Dragon-flies, or, as they are 

 familiarly called in this country, Devil's Darning-needles, and 

 Horse-stingers by our young naturalist friends in England. Hun- 

 dreds of beautiful lithographs in colors, drawings, cuts, plates, 

 and engravings throughout entomological literature have also 

 appeared, showing the vast variety and extraordinary forms com- 

 prising this group of the order Weuroptera, a group termed the 

 Odonata by Kirby and others, who divide it into the two families, 

 Libellulidce and Agrionidce. 



A great deal has also been written and printed upon the mar- 

 velous structure of these insects; their strange metamorphoses, 

 their habits and geographical distribution, much of which, owing 

 to its technical nature, cannot be touched upon in the present 

 connection. Moreover, in a popular work this will hardly be 

 necessary, as probably all the readers of this chapter are familiar 

 with the general appearance and parts of any of our typical 

 American dragon-flies. There is, for example, in the Eastern 

 United States, the big species that our boys and girls call the 

 Snake Doctor, firmly believing, when they see it hawking about 

 for its prey, that a snake lies concealed somewhere in the neigh- 

 borhood. Older folk call this insect the Mosquito Hawk, a name 

 more in keeping with its habits. Science recognizes two species 

 of it, designating them as /Escliua fieros and JE. grcmdis. As I 

 have said, it is a large form, and frequently gets into our houses 



