\ 



322 NATURAL HISTORY OF AQUATIC INSECTS CH.] 



abdomen of the male, and it is impossible to take 

 notice of a number of things at once. 



" Captive Ephemera of this species survived two or 

 three days, while those of Chloeon dipterum survived 

 several days after acquiring wings." ^ 



We owe to F. J. Pictet, a celebrated naturalist f)f 

 Geneva, some interesting particulars of the life-history 

 of Ephemerae. His classification of the larvae accord- 

 ing to their mode of life is instructive, though it is to 

 be regarded rather as a description of some well- 

 marked larval forms than as a zoological system of 

 any kind. He arranges the larvae as belonging to 

 one or other of the following groups : — 



I. Burrowing- Larva. — To this section belong the 

 Palingenia described by Swammerdam, the Polymit- 

 arcys described by Reaumur, and with less pronounced 

 habits the Ephemera vulgata, which forms the chief 

 subject of De Geer's observations. The body is long, 

 the head small, and the fore legs adapted for digging. 

 We may add that the respiratory organs bear many 

 filaments, and are therefore suited to passive aeration 

 of the blood by means of a current of water, as well 

 as capable of active respiratory movements. These 

 larvae inhabit slow streams with shores of cla}' or 

 earth, and make their burrows in the banks. Their 

 food is finely divided organic matter. 



Leptophlebia connects groups I and \\. It has 

 the tracheal gills filamentous, but united by a mem- 

 brane at the base. The legs show no adaptation to 

 digging. It occurs on the banks of the Rhone in 



1 Winged individuals of this species have since been kept 

 alive more than three weeks. 



