The Inhabitants of the Aquarium 295 



Boat-fly (Notonccta glauca) and others. 

 This interesting little group is represented 

 in our waters by six species. We frequently 

 find it with the Gyrinus, and it is of about 

 the same size as the latter. The hind lees 



o 



are strongly developed, being very long in 

 comparison with the fore and middle pair, 



Fig. 119. Boat-fly, Notonecta 

 glauca. 



and lined with stiff short hair. They serve 

 as a pair of very effective oars, and on ac- 

 count of their shape and position, very much 

 resemble them, thereby giving the insect its 

 name. The eyes are placed so as to enable 

 the insect to see upward and downward 

 equally well. Head and breast have a 



