CATFISH GENUS NOTURUS RAFINESQUE 213 



The tendency toward many branched caudal rays, the tall upper 

 procurrent caudal rays, the subterminal to almost terminal lower 

 jaw, and the broad band of premaxillary teeth favor N. gyrinus. 



N. miurus, as one parent, could contribute the irregular serrae 

 (in combination with gyrinus), the blotched appearance, and the single 

 internasal pore on each side. As in the hybrids, A^. miurus has eleven 

 preoperculomandibular pores and would be expected (in combination 

 with a parent having a terminal jaw) to produce a subterminal jaw. 

 The brownish black area near the tip of the dorsal fin and one which 

 extends to the margin of the adipose fin are features of miurus. The 

 same areas in A^^. miurus are black and diagnostic of that species. A 

 darkened band on the anal fin probably comes from N. miurus. 

 Several of the relatively low proportional measurements are also 

 characteristic of both parents. 



Hybrid vigor is indicated in the large individual as its extremely 

 large size has not been attained, rarely approached, by any speci- 

 men of the parent species that has been examined. Compared to the 

 hybrid (108.8 mm.), A^. gyrinus seldom reaches 90 mm., and A^. miurus 

 attains 88 mm. in standard length. It is possible ecologically for the 

 two species to hybridize. Neither is a typical riffle fish. Instead, 

 N. gyrinus seems to prefer slow current or standing water; N. miurus 

 prefers slow or moderate current. Both are found over mud or detritus 

 bottoms. N. miurus nests in cavities, and according to Hankinson 

 (1908, p. 208), A^. gyrinus was found nesting in "an old tin can," on 

 June 26, in Walnut Lake, Michigan. While it is possible that June 

 may be a little early in Michigan for miurus to spawn (they were 

 found spawning in late July and August in the Huron River), indi- 

 cations are that the breeding seasons of the species of Noturus may 

 overlap considerably. A^. gyrinus is probably common in the regions 

 whence the hybrids were taken and miurus is probably uncommon. 



I have not examined the only other known hybrid of this combi- 

 nation, described by Trautman (1948), but believe that his interpre- 

 tation is correct. His figure and data suggest an individual that is 

 intermediate in most respects (a hybrid) between Noturus gyrinus 

 and Noturus miurus. 



The ecological distribution of the two species in northern Ohio is 

 discussed by Trautman (1948, pp. 171-173). He found them spawning 

 close together under objects or in various types of cavities in south- 

 western Lake Erie, and feels that this is a breakdown rather than 

 an overlap of the ecological distribution. I interpret the distribution 

 of the species as broadly interfingering, and have examined several 

 samples from throughout the overlapping ranges of the two species 

 where both have been secured in the same collection. It appears 

 most probable that hybrids, in such circumstances of ecological 



