AUTICLE X V I 1 1 . 



Descriptions of New Species of I he Family Unionidse. By Isaac Ixa. Read March 5lh, 1852. 



It is now some years since I presented to this society a continuation of my discoveries 

 of new forms from the fresh waters and soil of the United States. Since that period, 

 owing to the kindness of many valued friends, I have been enabled to get together a much 

 larger number by far, than could have been anticipated. These have come chiefly from 

 localities hitherto little examined, and which have produced new species more or less in- 

 teresting. It will be observed that many are from Dr. Barratt, of Abbeville District, S.C., 

 from Mr. Tuomey, of Alabama, Dr. Hale, of Alexandria, Louisiana, Prof. Powell, of Mem- 

 phis, Major Le Conte, who procured them from Florida and Georgia, President Estabrook, 

 of Knoxville, Term., Mr. Joseph Clark, of Cincinnati, Mr. C. M. Wheatley, of New York, 

 and other kind friends. To them all, I return my sincere thanks for their liberality, and 

 I trust that they will be induced not to flag in the cause of American science, but rather 

 to be encouraged in the development of these new organic forms, which, in this branch 

 of Zoology exist in such vast profusion, and in so extended a number of species, in the 

 United States. 



Notwithstanding the vast number of well characterized species of the Family Unionidse, 

 (as there are also in the Family Melaniana,) there arc continually new and distinct forms 

 brought to our notice, which well deserve the attention of the American Zoologist. 



I am aware that many persons doubt the existence of so extended a production of 

 sprue-, but this arises from the want, of a knowledge of them, closely cultivated and 

 analytically examined. An organic form, instituted by nature must be recognised as dis- 

 tinct, for it will remain in a state of autonomy to the end of its term. It is the duty of 

 the zoologist to bring to tin 1 investigation an eye practised in discrimination, and a judg- 

 ment experienced in analysis, as will as also an honesl intention of purpose, that he maj 

 give the best and mosl accurate results to his investigations 



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