l66 Exchanges. 



Washington — Contributions from the United States National 

 Herbarium. 

 ,, Proceedings of the United States National 



Museum. 

 ,, Sifiithsonian Institution, Miscellaneous Collections. 



,, Year Book of the United States Department of 



Agriculture, 1920. 

 „ Smithsonian Physical Tables, 7th Edition. 



,, Publications of the United States Geological 



Survey. 

 York— Annual Report of the Yorkshire Philosophical Society, 



1920. 

 Zurich (Switzerland) — Vierteljahrsschrift der Naturforchenden 

 Gesellachaft in Zurich. 



