108 



GKOIvOGY OF IvA SAIvLE COUNTY. 



SUBGENUS PI^ANORBUIyA, HAI^DE. 



Seg-mentina armig-era, Say. — Shell has four 

 whirls, umbilicus deep, exhibiting- the volutions; aper- 

 ture subovate; oblique; far within the throat six 

 teeth; color brownish; breadth one-fourth of an inch. 

 Abundant. 



SUBFAMILY ANCYIvIN^. 



Genus Ancylus Geoffroy —River-limpet. Kty- 

 molog-y. Ancyhis {ag-kiilos,) a small round shield. 



Resembles in shape the marine are frag^ile 

 and small. We have a species which is about two-six- 

 teenth of an inch in leng-th, which I presume to be 

 Ancylus tardus, Say. I found numbers of them asso- 

 ciated with a valvata-like Phrygania, cling-ing- to 

 stones in Fox River. 



ORDER PECTINIBRANCHIATA— FAMIEY VAIvVATlD^ — 

 GENUS VAVEATA, MUEEER. 



Valvata tricarinata. Say. — Shell has three volu- 

 tions; three revolving-, carinate, prominent lines, g-iv- 

 ing- to the whirls a quadrate appearance; Suture deep; 

 umbilicus larg-e; aperture circular; lip simple, almost 

 surrounding- the aperture; shell horn colored, breadth; 

 one-fifth of an inch. Very abundant in ponds and 

 other waters. Easily known by the quadrate appear- 

 ance of the whirls, its round aperture, etc. 



Valvata sincera. Say. — This shell differs from the 

 former species in being- smaller, and is without the 

 carinated whirls. Same localities as the preceding- 

 species. Not so abundant. 



FAMILY VIVIPARID^. 



Genus Vivipara, Lam. — Numerous in all our rivers. 

 The animals are slug-g-ish in their habits. They live 



