11 



r>ut subsequent reflection has convinced me that first opinions 

 are not ahvays correct. The country drained by tlic Illinois, 

 Fox, and Vermillion rivers, and by our creeks, are the most 

 productive of shell-life. In fact, the wooded portions are 

 mainly within the drainage of these streams. At })resent, the 

 valley of the Fox is the most prolific of specimens. JIdix 

 iiUernata, is the most abuiulant species we have. Helix soU- 

 taria comes next. The other species are about equally divi- 

 ded as to numbers. The Bivalve MoUusca are numerous in 

 all our rivers. The Illinois river being the largest and empty- 

 in"- into the Mississippi, of cour.se produces the most si)ecies. 

 Ar the Starved Koek and in its vicinity, the river, here shal- 

 low, is literally filled with clams lying half buried in the sandy 

 bottom. On the North side of the Islaiul, also, a great many 

 are found. 



During the past summer, my nephew, A. C. Baldwin, of Deer 

 Park, and myself, while engaged in a clam hunt along the river 

 came to this locality. In a short time we secured a boatload 

 of the bivalves, including over twenty fine species. Having 

 glory enough for one day we returned home to boil them out. 

 'riie univalve ]Mollusca are very numerous in all our rivers, 

 creeks and ponds. Melantho suhsoUdus, Anthony, is the most 

 abundant form. Trxjpanostania suhulare, Lea, comes next. 

 Then, Tnj Zezmsii, Lea. The difference in the characters of 

 the univalve species within the distance of a few miles from 

 each other, is very apparent, produced, no doubt, by the con- 

 ditions of the station they occup}'. Some of the variations are 

 slight, it is true, but quite as marked as some that occur in 

 other species and which have been described as new. I have 

 no desire to increase the already enormous synonomy of Amer- 

 ican species by attempting to make new ones. Most of the 

 univalves may be found in a semi- fossil state in our recent de- 

 posits. Some fourteen years ago while I was examining the 

 remains of the trench and earthwork a short distance southeast 

 of the Starved Rock, and which is supposed to have been a part 

 of Fort St Louis, or connected with it, my attention was called 

 10 the abundance of a whitish substance mixed with the sand 

 alonjr the line of the fortification. On examination I found 



