14 



and ponds, such as Flag Lake at Havana. In the smaller 

 streams, where the current is often rapid, such as the Mackinaw, 

 the upper Sangamon, and the Little Wabash rivers, a number 

 of very interesting forms find their home, especially the 

 Sifnthemiime, Somafoch/ora and other Corduliime, and the species 

 related to Libellula. 



Of the third group, which live ii/ the mud or sand of the 

 bottom, there may be found in the streams just enumerated 

 other interesting material, especially Cordukgasfer, Progomphus 

 and Gomphus spiniceps. In this group the most definite selec- 

 tion of situations prevails. Where rapid currents flow over 

 rocky beds, as in the Mississippi at Rock Island, in the Mack- 

 inaw at the " Dells," and in the streams of Yellowstone Park, 

 is the chosen home of Diasfatouinia {Ophiogoinphus). Where 

 slow currents and a muddy bottom occur, as in many prairie 

 streams and ditches, Platheniis and LiheJlula, covered with 

 dirt, trail over the mud along the shores leaving a well-marked 

 track, or lie concealed amongst fallen trash, the dorsally pro- 

 jecting eyes of Plafheuiis enabling it to remain hidden and yet 

 keep a sharp lookout. The nymphs of the C or duleg aster idee 

 conceal themselves in the sand beneath the eddies of streams 

 or under the alluvial deposit in marshes, but do not burrow. 

 Each scratches a hole for itself, and descends into it like a 

 chicken into a dust bath, and, like the chicken, kicks the sand 

 over its back, and does not rest until almost hidden, only the 

 tops of its eyes, the tip of its treacherous labium, and the re- 

 spiratory aperture at the end of its abdomen reaching the sur- 

 face. The burrowers of the order are the members of the large 

 and as a whole abundant genus Gowphus. These burrow shal- 

 lowly along in the midst of abundant life, with the tip of the 

 abdomen turned up for respiration. Some are lake or pond 

 species, such as graslineUus and pHiUidus. The former is com- 

 mon in prairie ponds and in the small lakes near Chicago ; the 

 latter in similar localities, and in open lakes near Havana, such 

 as Matanzas and Clear lakes. Others choose the larger rivers, 

 being most numerous in quiet corners where flne rubbish and 



