38 PROCKEDINGS MANCHESTER INSTITUTE 



and surely an hj^pothesis may be permitted to stand as an hj^- 

 pothesis until shown to be irfconsistent witb known facts. The 

 small brook, for example, that crosses Smyth Road, and beside 

 which, in the meadows, are mud-holes formed by the removal of 

 muck for agricultural purposes, is at least a mile and a half dis- 

 tant from any permanent body of water — that is, such as Dorr's 

 or Stevens' Pond, capable of sustaining a prolonged drought. 

 It is improbable that the few individuals of L,eucorhinia intacta 

 and Sympetrum rubicundulum found here in September had 

 journej-ed so far with the benevolent purpose of restocking this 

 insignificant and depleted little stream. Plainlj^, however, if 

 these Dragonflies were not immigrants, they were of the old 

 stock and had survived, through special fitness, in the station 

 of their ancestors, an unusual period of drought. 



The n3'mphs of Dragonflies, from necessitj^, inhabit the mar- 

 gins of lakes and ponds, and the portions of streams where 

 the water is comparatively still. Clearwater, with a sandy or 

 otherwise clean bottom, is, of course, fatal to them, since thej' are 

 there exposed and must soon fall a prey to fishes and to one an- 

 other. When, as during the protracted droughts of 1899 and 

 igoo, the water in a lake or pond recedes until acres of marsh 

 are laid bare, some of the nymphs msty, and doubtless do, fol- 

 low the retiring water line ; but it is to find dangers increasing 

 many fold. As the character of the bottom changes, thej^ are 

 more exposed, and the fish are relativelj- more numerous b}^ 

 reason of the reduced area. Few Dragonflj'- n5'mphs could ex- 

 pect to survive under such conditions, and in a pool or brook 

 the situation is even worse. But there have been severe 

 droughts in this section of the country, certainly from the time 

 when the forests were cut away, and probably for centuries be- 

 fore, and yet the Dragonflies remain. It is at least plausible to 

 assume that some species have developed the capacit}- to lie 

 dormant in the dried or half-dried mud until the returning wa- 

 ter, at the end of the drought, shall revive them. 



Writers upon the Odonata have commonly attributed the dis- 

 tribution of these insects to their powers of flight, to favoring 

 winds, and to the transportation of eggs and nymphs by the 



