GEoivOGY OF r.A saivIve: county. 



113 



soft parts of the two I cannot speak as yet. These 

 species are now sometimes called Tryfanostovia, a 

 Genus instituted by Dr. Lea to take the place of Pleii- 

 rocera, Raf. The latter having- priority must stand. 



GENUS GONIOBASIS, LEA. 



Goniobasis livescens, Menke. — Ovate oblong-, 

 smooth, moderately thick, spire short, conically acute, 

 suture slig-htly impressed, whirls five to six, rather 

 flat, the last large, aperture larg-e, elliptical. Horn 

 color, purple within. Leng-th one-half inch, abundant. 



Goniobasis depyg-is. Say. — Oblong-, conic ovate, 

 whirls five, the last elliptical. Suture well impressed, 

 aperture narrow ovate, acute above, color yellowish, 

 two rufous bands on the whirls, shorter than G. live- 

 scens. Fox and Illinois rivers. 



Of more than two hundred and fifty species of 

 Goniobasis found in American waters, the two just 

 described are all inhabiting- this county. The latter 

 species is not so abundant here as the former. All our 

 StrepomalidcE are very hardy, living- sometime after 

 being- removed from the water, as I have had occasion 

 to notice, and differing- in this respect from the Vivi- 

 paridm. They are evidently suited to our northern 

 climate. 



Note. — Valvata We find by thousands in 



the Fox and Illinois rivers, fixed to stones, etc., the 

 larva case of an insect — Phryg-ania. The case is built 

 of g-rains of sand, cemented logether in the shape 

 of a valvata, for which it has been mistaken. 



CONCHIFERA — FAMILY CYCLADID^, WOODWARD — 

 GENUS SPHAERIUM, SCOPOEI, 



Sphaerium simile. Say — {S. sulcatum, Lam.) Shell 

 oval, truncated at the extremities in young-, and 



