188 FISHES OF ILLINOIS 



the young furnished with 6 to 10 well-developed retrorse teeth, whose 

 length is half, or almost equal to, diameter of spine, the teeth relatively 

 much smaller and more numerous in adults, in which their number ranges 

 from 10 to 25 ; humeral process longer and sharper than in A. melas. 



The brown bullhead, distributed throughout the length of the 

 state, is nevertheless the least abundant of our common horned 

 pouts. As remarked under the preceding species, it is peculiar in its 

 preference for stagnant waters, of both lowland and upland lakes 

 and ponds, and it is next commonest in the larger streams. Our fre- 

 quency coefficients are 1 .46 for glacial lakes, 1 . 25 for lowland lakes, 

 and . 94 for the larger rivers. We have found it most frequently in 

 the immediate course of the Illinois River, and have not taken it at 

 all in the northwestern part of the state, nor at any point within the 

 lower Illinoisan glaciation. 



Outside our area it is reported from lakes of New Brunswick to 

 those of the Saskatchewan system, including the Great Lakes in gen- 

 eral, and from thence southward to the Florida peninsula and to 

 Texas. It has been introduced also into many rivers of the Pacific 

 states, and into the small lakes of southern Oregon, in all of which it 

 has become excessively abundant. It is said by Bean to be the 

 commonest catfish in Lake Erie and its tributaries. It is the com- 

 mon bullhead or horned pout of New England and New York, but in 

 this state these names are much more likely to be applied to the 

 more abundant black bullhead (.4. melas), the commonest of its kind 

 in the smaller creeks. The present species is the principal bullhead 

 of the market catches from the larger rivers. 



The food of 13 specimens examined by us was unusually simple 

 for that of a catfish, consisting chiefly of small bivalve mollusks, 

 larvae of insects taken upon the bottom, distillery slops, and acci- 

 dental rubbish. One of the specimens had eaten eighteen leeches, 

 leeches appearing in the food of four others, and a few had taken 

 terrestrial insects and univalve mollusks. 



The adults are almost always more or less blotched or mottled, 

 all gradations between the well-mottled form (marmoratus) and the 

 typical brown nebulosus being found regularly in the same market 

 catches. These fishes have thick skin, and are easier to dress 

 than the yellow bullheads (.4. natalis). We have found both the 

 mottled and the brown forms, with occasional specimens of the 

 black bullhead (A. melas), indiscriminately referred to as "bull- 

 pouts" or "speckled bullheads" by the fishermen who were dressing 

 them. 



