76 ILLINOIS ACADEMY OF SCIENCE 



The five and a half feet of silt and peat above the shell de- 

 posit represent the later stages of this locality and indicate its 

 change from a river to a lake and finally to its present marsh- 

 bog character. The mollusks (42 species) and other remains 

 of life found in this deposit are listed below.* 



Mollusca 

 Symphynota compressa (~Lea)=pressus Lea 

 Symphynota costata (Rai)=rugosa Barnes 

 Anodonta grandis footiana Lea 

 Anodontoides subcylindraceus (Lea) 

 Alasmidonta calceola (Lea)=deltoidea Lea 

 Eurynia iris (Lta)=novi-eboraci Lea 

 Eurynia ellip sif ormis (hea)=spatulatus Lea 

 Lampsilis ventricosa (Barnes) 

 Sphaerium simile (Say) 

 Sphaerium striatinum (Lam) 

 Pisidium near abditum Prime 

 Pisidium compressum Prime 

 Pisidium medianum Sterki 

 Pisidium milium Sterki 

 Pisidium pauperculum Sterki 

 Pisidium roperi Sterki 

 Pisidium ventricosum Prime 

 Pisidium near vesiculate 

 Campeloma integrum (Say) 

 Campeloma integrum obesum (Lewis) 

 Campelima subsolidum (Anth) 

 Pleurocera elevatum (Say) 

 Goniobasis livescens (Menke) 

 Valvata tricarinata Say 

 Amnicola limosa (Say) 

 Amnicola lustrica Pilsbry 

 Physa ancillaria Say 

 Physa integra Hald 

 Physa heterostropha Say 

 Ancylus rivularis Say 

 Planorbis antrosus Conrad 



Planorbis campanulatus Say (=bicarinatus Say) 

 Planorbis trivolvis Say 

 Planorbis deflectus Say 

 Planorbis parvus Say 

 Galba obrussa (Say)=disidiosa authors 

 Galba humilis modicella (Say) 

 Lymnaea stagnalis appressa Say 

 Carcychium exiguum (Say) 

 Succinea ovalis Say 

 Strobilops labyrinthica (Say) 

 Vitrea hammonis (Str'6m)=radiatula Aid 



Arthropoda 

 Head of dipterous insect. 



Vertebrata 

 Mammut americanus (Kerr) 



Considerable driftwood was observed, but none was identi- 

 fied. The shells occurred in little colonies, just as they are 

 found today. It is probable that these colonies represent lo- 

 calities where the water had brought together and deposited 



3^ Walker Nautilus, XI., p. 121; XIII., p. 34; 55. 



