204 



A. M. KDWAKUS ON A DlATOMACEUUS KAKTH. 



Mexicana, by-the-bye, is C. Americana^ Ehr., when the striae are 

 fine, or as Ehrenberg says in the American tabulae (Abhand. 

 Berl. Ak., 1843, p. 123), " striis obsoletis." 



Besides the Guatemala Diatomite 1 wish to report on a clay 

 from Hatfield Sw amp, N.J. , which is two miles and a half long 

 by one~and a half broad, and three feet eight inches deep, 

 which contains also, besides fresh water forms, such as Navi- 

 cula viridis, Ehr., in its various forms of nobilis, gigas, and 

 others, and Eunotia gracile, Biddulphia Icevis, Ehr. It has also 

 two truly marine species that have never been found in fresh 

 water ; these are Actinocyclus Balfsii, W. S., and Gam pylodiscu s 

 echineis, Ehr. 



~^Now" the first water that fell was rain, fresh water, and 

 Diatomacese grew, died, and their shells were deposited on the 

 floor of the sea, or ocean, as fresh water forms. Thereafter the 

 fresh water dissolved the salts that were present, and became 

 marine or what we call salt water. The Diatomaceas were 

 gradually changed as the water became more and more salt, 

 and became marine species, so that the Diatomaceae appeared 

 at first as fresh water forms. 



Analysis of a Sample of Diatomite from Guatemala. 

 By Mr. A. Ashe. 



Moisture 

 * Combined Water and Organic Matters 

 Oxide of Iron (Ee.Og) 

 Alumina 

 Lime... 

 Magnesia 

 Potash 

 Soda... 



Phosphoric Acid 

 Carbonic Acid 

 Sulphuric Acid 

 Chlorine 

 Silica 



7-610 



6-570 



3-028 



4-872 



-515 



122 



•104 



-146 



-118 



•240 



None 



•010 



76665 



100000 



* Containing nitrogen in the organic matter, '034. 



