

I 



II 



III 



IV 



V 



VI 



AnodontoidGs ferussacianus subcylindracBus 















(Lea) Simp. 







3 









Anodonta imbecillis Say 









3 



3 





Anodonta grandis Say 





2 



2 



2 



2 





Anodonta footiana Lea 







1 









The foregoing list is based chiefly on collections made by the 

 writer, but additional material was obtained from Dr. Stephens 

 and Mr. Tenney. A partial list of the moUusks of this region 

 was included in the paper on ''Alluvial Fossils and Modern 

 Drifted Shells, ' ' published by the writer as a supplement to the 

 address of the vice-president of Section Am. Ass'n for the 

 Advancement of Science, 1913. A smaller list was also pub- 

 lished in The Iowa Geological Survey, vol. XX, p. 329 ; 1910. 



Undoubtedly other species will be found, and to assist the stu- 

 dent in determining such discoveries a key to most of the mol- 

 lusks known from the state is appended. A more complete 

 list and key will be published in the near future, and this will 

 include all the bivalves known from the state, the present key 

 giving only those which are known from this territory. A more 

 critical review of the nomenclature will then be included. For 

 the present the writer makes use of certain well-known names 

 which are probably no longer tenable. 



The key consists of tv/o parts, the first being a key to the 

 genera, and the second to species. The numbers following the 

 generic names in the first key correspond to the numbers pre- 

 ceding the same names in the second part. 



KEY TO THE GENERA OF MOLLUSCA OF IOWA 



I — Animal without external shell; terrestrial. 



Slug mottled, light colored, more than 75 mm. long ; no internal shell. 



Genus PHILOMYCUS 1 

 Slug not more than 25 mm. long, darker and more uniform in color. 

 Mantle covering whole body; no internal shell. 



Genus PALLIFERA 2 

 Mantle covering only anterior part of body; with rudimentary 

 shell. Genus AGEIOLIMAX 3 



II — With univalve shell. 



A — Operculate, mostly aquatic. 



a — Shell more than 10 mm. long. 



1 — Whorls distinctly flattened, spire exserted, conical. 

 Aperture with notch or short canal. 



Genus PLEUEOCERA 4 



75 



