MATURE COMMUNITIES 149 
snail (Planorbis trivolvis) (Fig. 112), and the amphipod (Eucrangonyx 
gracilis) (Fig. 113). All these occur in the senescent stage, where in 
dry years the pond goes almost dry. The vertebrates of the mature 
and later stages are not numerous. The fish are limited to mud- and 
muck-preferring species, the black bullhead (Ameiurus melas) and the 
mud minnow (Umbra limi) (106). The grass pickerel and the dogfish 
are found in such vegetation-choked ponds. 
105 
104 ® ® 
REPRESENTATIVES OF THE EMERGING VEGETATION ASSOCIATION (POND 14) 
Fic. 102.—The common newt (Diemictylus viridescens); natural size (after Hay). 
Fic. 103.—A flat pond snail (Planorbis campanulatus); natural size. 
Fic. 104.—TJhe common pond snail (Lymnaea reflexa); natural size. 
Fic. 105.—Small flat snail (Planorbis parvus); 3 times natural size. 
Fic. 106.—A snail (Planorbis hirsutus); 3 times natural size. 
Fic. 107.—A predaceous diving beetle (Cybister fimbriolatus Say); natural size. 
Fic. 108.—A soldier-fly larva—unidentified; twice natural size. 
The amphibia are the frogs which occur in all stages of the associa- 
tion, and the common salamander (A mblystoma tigrinum), which burrows 
in the soft mud where it remains during the greater part of the year. 
It comes out in spring (February or March) and deposits eggs in the 
pond, where the young are found later. Of the turtles the common 
