Unionidie of Spoon River. 



THE UNIONID^ OF SPOON RIVER, FULTON 



COUNTY, ILLINOIS. 



By W. S. Strode, M. D. 1 



This report or review of the Unionidie of Fulton County, 

 Illinois, is based mainly on researches made on Spoon River, a 

 tributary of the Illinois and at a point about twenty miles 

 from its mouth. It is a sinuous, winding stream, something over 

 100 miles long and with a width varying from 100 to 150 feet. 

 The valley through which it courses averages about one mile 

 in width. In many places cultivated fields come up to the 

 very banks of the stream, and then alternate with strips of 

 timber, or a fringe four or five rods wide of willow, silver maple 

 or elm, is left by the thrifty farmer to protect and hold the 

 banks. Occasionally a great white-armed sycamore is still to 

 be seen, a veritable giant left standing as a memento of the 

 great forest that once filled all this beautiful valley. 



The bed and banks of the stream present a variety of con- 

 ditions suitable to the tastes and habits of a large number of 

 the Unionidse. 



Deposits of black mud, or of mud and clay, sand-banks, and 

 long stretches of rockv or pebbly bottom covered with a suffi- 

 cient deposit of mud and sand to afford a burrowing place 

 for the molluscs of the river. 



The river is a clear-running spring-fed stream, with but little 

 iron, lime or other corroding substances to damage or disfigure 

 the shells; consequently they grow to a size and attain a 

 beauty of markings and coloration not often excelled in the 

 same species found in other water courses. 



My observations have for the most part been confined to a 

 part of the stream lying within four or five miles above and 

 below the village of Bernadotte, and at such odd times and 

 moments as a busy practitioner could spare from a large 

 country practice. Provided with a bag or basket, and attired 

 in gum boots reaching to the hips, a hurried run would be 



