78 PROCEEDINGS OF THE AMERICAN ACADEMY 



Science, which prefers facts to hypotheses, has not yet sufficient 

 materials to assure us whether, and by what means or in what ways, 

 the original species were first diffused from single centres over distant 

 parts of the earth ; but all we know of the arctic and northern regions 

 shows that their vegetation is very homogeneous. This synopsis may 

 help to show, with regard to Willows, that there are many links con- 

 necting Europe and America. 



[Note. — There are about ten species of Salix from Oregon and the 

 Rocky Mountains described, and two or three of them figured, in Nut- 

 tail's North American Sylva, which remain unknown to Prof. Anders- 

 son : all or most of them he may be able to identify, when the volume 

 reaches him, with species enumerated in this Synopsis. A. G.] 



Four hundred aud fifty-fix'st meeting. 



May 11, 1858.— Monthly Meeting. 



The Academy met at the house of B. A. Gould, Esq. 



The President, and afterwards the Vice-President, in the 

 chair. 



The Corresponding Secretary read the following letters, 

 viz. : — From the Academic des Sciences, etc. de Dijon, Jan- 

 uary 18, 1857 ; Societe des Sciences Naturelles de Cherbourg ; 

 Det Kongelige Danske Videnskabernes Selskab, June 30, 

 1857 ; K. Akademie der Wissenschaften, Wien, August 10, 

 1857 ; Koyal Society of Sciences, Upsal, October 11, 1857 ; 

 Societe Linneene de Normandie, November 29, 1857 ; Trus- 

 tees of Boston AthenaDum, April 10, 1858 ; and the Boston 

 Society of Natural History, May 1, 1858, acknowledging the 

 receipt of the Academy's publications ; — from the Director 

 der Sternwarte, Breslau, October 23, 1857, in acknowledgment 

 of the same, and presenting a work on Climatology; — from 

 the Academic des Sciences de Dijon, January 18, 1857 ; Det 

 Kongelige Danske Videnskabernes . Selskab, June 30, 1857 ; 

 K. Academie der Wissenschaften, Wien, December 17, 1857 ; 

 Universite Royale de Christiania, November 10, 1857 ; Nich- 

 olas Manzini, Havana, December 10, 1857 ; and Colonel J. 



