/t^y Ac 3<-'^/.f^c 



0158ERVATIONS 





^ Or r 



GENUS UN 10, 



DESGRIPTIOxXS OF x\E\V SPECIES, TIIEIll SOFT PARTS, AND EMBRYONIC FORMS, IN 

 THE FAMILY UNIONID.E. 



READ BEFORE TUE ACADEMY OF NATURAL SCIENCES OF PUILADELPUIA, AND 

 PUBLISHED IN TUEIR JOURNAL. 



♦- . 



ISAAC LEA, LL. D., 



rRBSlUEXT OF rUK ACADEMY OK NATl'BAL A'naxES, ETC. ETC. 



WITH SIXTEEN PLATES. 



VOL. 8.-PART I. 



I'llILADEH'UIA : 



PRINTED FOR THE AUTHOR. 



