

CONTENTS. 



ART. I.— Description of fifty-two Species of Unionidse. By Isaac Lea* . 5 



II. — Supplement to Isaac Lea's Paper on Unionidee f • • . ^5 

 III. — On the Homologies and Origin of the Types of Molar Teeth of 



Mammalia Educabilia. By Edw. D. Cope $ . . . v ^^ 



* Extra copies printed for the Author ' . 



4. (<- << U .•< 



t " " " " March 30, 1874. 



