WATER MARGIN COMMUNITIES 181 



close to the water. The tiger-beetle of the Lake Michigan shore is dis- 

 placed by that of another (Cicindela repanda) which is less active. With 

 these is the hooded grouse locust (Paratettix cucullatus) (Fig. 137) (40, 

 p. 419). The small semiaquatic snail (Lymnaea modicella) is frequently 

 present in numbers. 



The nests of the spotted sandpiper (108, 141) and the yellowlegs are 

 found here, and the birds no doubt feed upon the invertebrates present 

 on the margins of the ponds and of the shallow water. 



c) Association of sedge margins of ponds and small lakes (Stations 

 32-34; Tables XL, XLI). — As time goes on, the sandy margin is 

 captured by sedges which are scattered at first, so that the animals just 

 discussed continue for a time among them (Figs. 138, 139). Finally, 

 however, the ground becomes sodded over 

 with sedges and a low prairie animal commu- 

 nity comes in, and the bare ground animals 

 disappear. In the case of ponds which are 

 to develop into forest this stage is found 

 only along the young ones. The sedges are 

 soon displaced by shrubs and the sedge 

 communities give way to shrub. 



d) Associations of shrub margins of ponds 

 and small lakes (Fig. 140) (Stations 34, 37, 

 44; Tables XLI, XLII).— Mr. Allee has 

 verified my observations to the effect that . Fl ^ ^--Hooded grouse 



. locust {Paratettix cucullatus) 



the aquatic part of this formation is almost ( a f ter Lugger). 



entirely barren; however, in summer we get 



the short-winged and armed grouse locust (Tettigidea armata Morse, 



and parvipennis Harr.) (40) and the slimy salamander (Plethodon 



glutinosus) (152) (Fig. 141). Of the birds associated with the water 



we have here the wood-duck and the green heron. 



4. MARGINS OF RIVERS 



(Station 29) 

 Here the sandy margin is similar to that of the ponds and lake. 

 Along the Fox River we find the mole cricket (40) which burrows into 

 the sand. Mud margins are rather barren except for occasional beetles. 

 The margins of rivers which are grassy or marshy are like those of ponds 

 and lakes. The margins of the Calumet and lower Deep rivers are 

 covered with marsh plants and saturated with water in spring. They 

 are the nesting-places of the long-billed marsh wren (Figs. 142, 143) and 

 many other marsh birds (108, 153). 



