OBSERVATIONS 



GENUS UNTO, 



TOKKTHEl! WlXn 



DKvSr'BIPTIONS OF NKW SI'KOIES, TIIEIll SOFT I'AllTS, AND EMBRYONU' FORMS, IN 

 THE FAMTEY UNIONID^. 



RRAP HEFORE THE ArADEMY OF XATUUAL SCIENCES OF THILADELPHIA AND 

 PURM.SflEP l\ THEII! JOURNAL. 



BY 



ISAAC LEA, LL. D., 



PRESIDENT OF THE ACADEMY OF NATURAL SCIENCKi! OF PniLADELrHlA, ETC. 



WITH THIRTEEN I'LATES. 



VOL. 7.-PART II. 



PHILADELTHIA: 



PRINTED FOR THE AUTHOR. 



