204 FISHES OF ILLINOIS 



disturbed first dart away to a little distance, and then bury 

 themselves, tail downwards, in the mud with one or two quick 

 twists of the body. They have also the singular habit of burrow- 

 ing into the mud when the water evaporates from a pond. 

 Professor Baird says that a locality which, with the water 

 perfectly clear, will appear destitute of fish, will perhaps yield 

 a number of mudfish on stirring up the mud at the bottom and 

 drawing a seine through it. Ditches on the plains of Wisconsin, 

 or mere bog-holes containing nothing else beyond tadpoles, 

 may thus be found full of mudfish. 



The intestine is short, less than the body in length, the gill- 

 rakers are thick and rather long, about half the length of the 

 filaments, and the pharyngeal apparatus is insignificant. The 

 food of ten specimens taken from six localities consisted largely 

 of minute duckweed (Wolffia) and unicellular alga?, insects and 

 crustaceans making, however, more than a fourth of the food. 

 The latter were mainly Entomostraca. Thin-shelled univalve 

 mollusks (Physa) were taken from two of the specimens, and 

 amphipod Crustacea (Crangonyx) from one. Dr. Abbott reports 

 that he has seen mud-minnows leap out of the water a distance 

 greater than their length to catch insects resting on blades of 

 grass. 



They apparently spawn in early spring, and Abbott reports 

 that in New Jersey he has found them apparently ripe on the 

 16th of March, and that even earlier than this they were making 

 their way up stream in small brooks, leaping from eddy to eddy, 

 evidently on their way to their spawning beds. We have 

 found ripe females during the first week of April at Havana. 

 Dr. Ryder says that their adhesive eggs are laid singly upon the 

 leaves of aquatic plants. Those observed by him, hatched on 

 the sixth day. 



This little fish is rather peculiarly distributed in Illinois, 

 occurring in our collections almost entirely in the extreme 

 northern and the extreme southern parts of the state. We have 

 elsewhere taken it only at Havana and Meredosia, on the Illi- 

 nois River, where it has occurred ten times in nearly eleven 

 hundred collections. Its frequency coefficients are correspond- 

 ingly unequal for the three sections of the state, those for south- 

 ern and northern Illinois being 1.48 and 1.28 respectively, while 

 that for central Illinois is but .23. We have found it most 

 frequently in lakes and ponds, and next in the smaller rivers. 



