OltSEKVATIONS 





GENU8 UNIO 



TUIIETUEK WITU 



DESCRIPTIONS OF NEW SPECIES, THEIR 80FT PARTS, AND EMBRYONIC FORMS, IN 

 THE FAMILY UNIONID.E. 



READ BEFORE THE ACADEMY OF NATURAL SCIENCES OF PHILADELPHIA, AND 

 PUBLISHED IN THEIR JOURNAL. 



ISAAC LEA, LL. D., 



PRESIDENT OF TUE ACADEMY 0I> NATURAL SCIENCES, ETC. ETC. 



WITH SIXTEEN PLATES. 



VOL. 8.-PART I. 



PHILADELPHIA : 



PRINTED FOR THE AUTHOR. 



