FIELD BOOK OF PONDS AND STREAMS 



over which the male keeps close guard. In late May and 

 June he cleans a space on the bottom, about a foot across and 

 several inches deep, fanning gravel away with his tail and 

 pulling heavier stones with his mouth. Then he brings a 

 female to the nest and the two swim round and round with 

 their ventral sides close together while eggs and clouds of 

 sperm cells are discharged into the water. Soon after this 

 she departs, leaving him to guard the eggs, which become at- 

 tached to the small stones and gravel of the nest bed. 



Size. — 8 inches. 



Distribution. — Very common, especially in ponds; Maine 

 to Minnesota, southward to Florida, but less abundant there. 



Fig. 280. — Small-mouthed black bass, Microp- 

 terus dolomieu. 



Small-mouthed black bass, Micropterus dolomieu. — Fa- 

 mous as sportsmen's fish, both the small- and large-mouthed 

 black bass are well known and widely distributed in clear, 

 cool waters, streams and stream-fed ponds with rocky bottoms. 

 They thrive where crayfishes are abundant, these being the 

 favorite food of the adults. 



Neither of the black basses is black. The small-mouthed 

 species is silvery to golden green with indistinct darker cross 

 bands; the large-mouthed black bass is green, darkly mottled 

 on the back and along a line on each side. But both vary 

 greatly in color and can only be distinguished by structure. 

 The small-mouthed bass has only a moderate sized mouth 

 (Fig. 280) and its angles do not extend backward behind the 



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