SMITHSONIAN MISCELLANEOUS COLLECTIONS. 



253 



LAND AND FRESH-AVATER SHELLS 



OF 



NORTH AMERICA. 



PART IT. 



STREPOMATID^ 



(americax mela>"ians). 



GEORGE W. TRYON, Jk. 



WASHINGTON : 



SlillTHSONIAN INSTITUTIOX 



DECEMBER, ISTS. 



