222 NORTHERN FISHES 



other Minnesota darters. It is bright green, blotched with dark brown, 

 and has about 11 reddish spots on the sides. The belly is greenish yellow 

 to almost white and is overlaid between the base of the anal and pectoral 

 fins with an orange band; there is a band before the eye and one below 

 it. The upper half of the spinous dorsal fin, except the margin, is a bril- 

 liant orange, with a very dark edge. The scales number 5-59-9. The 

 dorsal fin has 9 spines and 11 soft rays. The anal fin has 2 spines and 7 

 soft rays. This darter reaches a length of 2 inches. Spring males have 

 exceedingly brilliant and beautiful coloration. 



This species has been a difficult one to describe and delimit, for most 

 of its characteristics are variable. In all the specimens examined by 

 Carlander (1941), who has made a detailed study of this species, the 

 cheek, opercles, and nape were completely scaled, but the breast was 

 naked; the gill-membranes were slightly or not at all connected. In 

 about half the Minnesota specimens studied the lateral line was almost 

 straight; in other specimens there was considerable anterior arching. 

 The number of scales in the lateral line varied from 49 to 69. a larger 

 range than is reported elsewhere for this species. 



In no case was the lateral line complete. Usually about half the scales 

 were without pores. Dividing the number of pored scales, together with 

 the unpored scales to the last pored scale, by the number of unpored 

 scales gave a measure of the completeness of the lateral line. The fre- 

 quency distribution of this measure was as follows: 



Completeness of 



lateral line 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.6 



Number of fishes 1 1 6 5 7 9 10 3 1 2 1 1 



The dorsal fin had 7 to 10 spines, usually 9. The variation in this char- 

 acter was as follows: 7 spines in 3 fishes. 8 in 27, 9 in 62, and 10 in 12. 



A general characteristic often used in separating this species from 

 others is the number of soft rays in the dorsal fin. This species has 9 to 

 11. whereas others have 12 to 15. Some Minnesota specimens were found 

 to have 12 rays; however, in counting these rays the last, a forked ray, 

 was counted as one, though at times it was difficult to determine whether 

 it was one forked ray or two separate rays. These Minnesota specimens 

 with 12 rays were collected with other specimens having fewer rays, 

 from which they were undistinguishable except for this difference. The 

 Minnesota specimens had from 9 to 12 rays. There were 9 rays on 4 

 fishes, 10 on 33, 11 on 63. and 12 on 9. 



This species ranges from Saskatchewan to Quebec and southward to 

 Colorado, Iowa, Illinois, Indiana, and Ohio. The Iowa darter is very 

 common throughout the lake region of Minnesota, from the Iowa line 

 northward. It is found in Lake of the Woods and Lake Vermilion. It 

 is commonly found in the weedy margins of lakes as well as streams. 

 It is common in all parts of Wisconsin (Greene, 1935) . Forbes and 

 Richardson (1908) reported it as spawning in April and May. 



