A. M. Edwards — Deposit of Diatomacece. 385 



Art. XLIII. — On a Champlain (?) deposit of Diatomacew be- 

 longing to the Littoral Plain ; by Arthur M. Edwards, 

 M.D. 



Ojst the 30th of March, 1859, F. C. S. Eoper read a paper 

 by me before the meeting of the Microscopical Society of 

 London, and which was published in volume vii of the 

 Transactions, " On Diatomacese collected in the United States." 

 In it there is spoken of a gathering made at Hoboken, N. J., 

 in which eighty-six species of Diatomacese, from fresh, brack- 

 ish and salt water are mentioned as coming from that locality. 

 This gathering, or rather these gatherings, for there were more 

 than one hundred made at that time, were mostly from a large 

 brook, the mud of which yielded the -shells of the dead Diato- 

 macese. At that time I did not try to work out the geology 

 of the deposit, only pointing out that the mixture of marine, 

 brackish and fresh water forms in the deposit was curious. 

 Since that time I have kept the matter in view and am now 

 prepared to assert what I believe to be the geology of the 

 deposit. I shall show that the Diatomacese in it, and by 

 which its geology is determined, are widely spread. 



It is the first time that Diatomacese are found at all in the 

 geological scale and referred to the brackish, although they are 

 indicated by Ehrenberg in the Mikrogeologie, 1854, as coming 

 from Norwich, Conn. This I will show is the same es those. 



They are known to be marine and are referred to the Eocene, 

 Oligocene or Miocene Tertiary. These are from Paita, Peru ; 

 San Pedro (or farther south in Southern California) to Sub 

 Little Mines, Del Norte Co., in California ; Petersburg, Vir- 

 ginia, to Atlantic City, New Jersey ; Oran, in Africa ; Mors, 

 in Denmark ; Simbirsk, in Russia ; Sentz Peter, in Hungary ; 

 Moron, in Spain ; Nicobar Island, in the Bay of Bengal ; 

 Cuba, Trinidad and Barbadoes, in the West India Islands ; 

 Sandai, Kobe and JSTetanai, in Japan ; the Island of Sicily and 

 Omaru, in New Zealand. 



On the 18th of December, 1871, I read a paper before the 

 Lyceum of Natural History, New York, " On a deposit of 

 marsh-mud upheaval by superincumbent pressure and contain- 

 ing the remains of shells of Mollusca and microscopic organ- 

 isms," which was not then published, but is now for the first 

 time in the microscopic notes for January 1, 1893. As this 

 records the instance of the shells of marine and brackish 

 Diatomacese in this deposit also, it now sees the light. The 

 third instance of marine, brackish and fresh-water Diatomacese 

 mixed I have now to publish. This deposit I have studied 

 for over three years past. Besides the many spots on the 



