BROOK, CREEK, AND RIVER 



283 



spines of segment nine are sharp, divergent, and longer than 

 the appendages of segment ten, it is a nymph of Tetragoneuria; 

 while if the spines of nine are 

 incurved and not longer than 

 the appendages of ten, the 

 nymph is thztolSomatochlora. 

 If the fish of the streams 



are Studied, again we find FIG. 431 Rainbow darter, Etheostoma 

 Certain Species in the head- coeruleum, two-thirds natural size. 



waters, others coming in ^c^HT 



down in the mid-course, still 



others not appearing until the 



river stage is reached, and 



finally some largely confined 



to the estuary. Streams that 



are mere brooks, short and 



small, will have the same sort 



of fish that are found near 



the headwaters of the larger 



rivers. The horned dace 



(Fig. 427) is apparently the fish that works its way farthest 



upstream, often living in the pools of brooks that otherwise 



FIG. 432. Head of common sucker, 

 Catostomus commersonii, one-third natural 

 size. 



FIG. 433. Stone roller, Campostoma anomalum 



have dried up. The red-bellied dace (Fig. 428) and the black- 

 nosed dace are not far behind it. The blunt-nosed minnow 

 (Fig. 429), Johnny darter (Fig. 430), and the rainbow darter 



