146 



POND COMMUNITIES 



4. THE ASSOCIATION OF EMERGING VEGETATION 



(Stations $4~37, 39> Ponds 5, 7, and 14) (Fig. 101) (30 and 52) 

 With the incoming of the water-lilies and the fine-leafed plants, we 

 have the inauguration of a new state of affairs. Among the new animals 



1 



! a 



c 



99-/-. - A- 



Representatives of the Dense Bulrush Association (Pond 5) 

 (All about natural size) 



Fig. 95. — The common diving spider (Dolomedes sexpunctatus) . The individual 

 from which this drawing was made was taken with a nymph of the dragonfly shown, 

 in its jaws. 



Figs. 96, 97, 98. — Various stages of a dragon-fly (Leucorhinia Intacta) : 96, nymph; 

 97, about to shed its outer covering; 98, the adult. (Modified from Needham.) 



Fig. 99. — The larva of a caddis- worm (Phryganeidae) , which makes its case from 

 bits of grass blades, etc. 



Fig. 100. — Small gill-breathing snail (Amnicola limosa). 



that come in, the bivalved mollusks deserve special mention. The 

 Unionidae must have bare bottom for their activities; they are too large 

 and heavy to climb on such small vegetation, and the development of 

 such a habit has not taken place. They disappear with the sparse 



