188 FISHES OF ILLINOIS 



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 frequency 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 Illi- 

 nois River, and have not taken it at all in the northwestern part 

 of the state, nor at any point within the lower Illinoisan glacia- 

 tion. 



Outside our area it is reported from lakes of New Bruns- 

 wick to those of the Saskatchewan system, including the Great 

 Lakes in general, 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 common 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 (A. 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 accidental 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 mot- 

 tled, 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 (A . natalis) . We have 

 found both the mottled and the brown forms, with occasional 

 specimens of the black bullhead (A. melas), indiscriminately 

 referred to as "bullpouts" or " speckled bullheads" by the 

 fishermen who were dressing them. 



