From the American Journal of Science and Arts, 2nd Series, Vol. XIV. — Nov., 1852. 



FACTS AND PRINCIPLES 



RELATING TO THE ORIGIN 



AND THE 



GEOGRAPHICAL DISTRIBUTION 



MOLLUSC A 



By THOMAS B L A N D, F. G.S., London. 



In preparing this paper, the following works have been par- 

 ticularly consulted, viz, — Introduction to the Mollusca of the 

 United States Exploring Expedition. By A. A. Gould, M.D. 

 December, 1851 ; and Catalogue of Shells collected at Panama^ 

 with Notes on their Sytionymy^ Station^ and Geographical Dis- 

 tribution. By C. B. Adams, Professor of Zoology, &c. in Am- 

 herst College, Massachusetts. New York, 1852. 



We estimate these works as highly valuable contributions to 

 science, and especially so with respect to the subject of the 

 geographical distribution of Testaceous Mollusca. 



The attention of these authors has for some years been directed 

 to this question. It is discussed by Dr. Gould in his '■^Report 

 on the Invertebrata of Massachusetts,^^ dated March, 1840, — also 



Second Series, Vol. XI Y, No. 42.— Nov., 1852. 50 



