254 



Margaritana rugosa and TJnio luteolus. No two series, from the different areas, 

 present exactly the same facies. So marked is this, in some cases, that the lake 

 forms can always be separated from those which were obtained in streams. This 

 general study is reserved for more abundant data and final discussion on another 

 occasion. 



A further study of the geographic tables will demonstrate that the richest 

 shell faunas occur in the Wabash and the Ohio drainages, these two areas furnish- 

 ing nearly the same species in common, though many of each are not generally 

 distributed over the State. Of the shells which are both common and yet limited 

 in distribution Unio ebenus, TJnio irroratus and Unio cewpus among the bivalves, 

 and Campetoma ponderosinn and Pleurocera canal iculatum among the univalves will 

 serve as types. The differences between the two basins may be noted from the fol- 

 lowing lists: 



OHIO BASIN. 



Unio camelus. 

 TJnio varicosus. 

 Unio cincinnatiexsis. 

 TJnio foliatK.". 

 TJnio dorfeuiiiianiis. 

 Sphaerium staminei(m. 

 Anculosa praro-'^a. 

 Anculosa triliueuta. 

 Anculosa carinafa. 

 Ooniobasis bicolorata. 

 Ooniobasis depygi^. 



GONIOBASIS INFANTULA. 



Goniobasis Informix. 

 Ooniobasis intersiki. 

 Goniobasis loi'isvillensis. 



Pleurocera simplex. 

 Amnicola cincinnatiensis. 



WABASH BASIN. 



TJiiio personatus. 

 Unio sampsonii. 

 Anodonta suborbiciilaia. 

 Margaritana confragosa. 

 Sphnericum sphaericum. 

 '^Sphcrium fabale. 

 Goniobasis spartenburqhensis. 

 Goniobasis livescens. 

 Goniobasis cubicoides. 

 Angitrema armigera. 

 Meseschiza grovesnorii. 

 Pleurocera troostii. 

 Vivipara subpurpurea. 

 Viripara contectoides. 

 Viripara intertexta. 

 Menetus exacutus. 

 Campeloma decisum. 

 Campeloma rufuni. 

 Campeloma subsolidum. 

 Limnophysa caperata. 

 Planorhella campanulatn . 



•■'Not seen ; adiuitted to the list on the authority of Temple Prime, vide " Catalogue of 

 the Species of Corbiculada-," p. 10, 18t5i. 



