118 THE MICROSCOPE. Aug. 



plutonic. But recent search has revealed these deposits, 

 or some very like them, in districts which are non-vol- 

 canic, and they are not always sub-plutonic. But I will 

 not now go into the cleaning of these nor of the marine 

 fossil gatherings, such as those of Richmond, Va., and 

 California, for this paper treats only of the quick me- 

 thod of cleaning the shells. It also records a method of 

 cleaning without the use of nitric acid, which is always 

 troublesome to use, being dangerous also both to the 

 health and the clothes. In the method which I have 

 detailed we have only carbon dioxide given off in small 

 quantity, and the red fumes can be eliminated by the 

 window or out of doors. The process is easy of use and 

 yields very nice preparations. 



The Origin of Fresh Water Clays in New Jersey, With 

 Correlation of Clays in Other States. 



By ARTHUR M. EDWARDS, M. D. 



NEWARK, N. J. 



I have been studying the fresh water clays in New 

 Jersey for three years and this is the conclusion that I 

 come to at present. 



I have described in the Microscopic Notes nine de- 

 posits from the iceberg period, which includes fresh wa- 

 ter, fossil, sub-peat and lacustrine sedimentary deposits 

 of bacillariacese (diatomacese), as they were called when 

 first discovered as lying in the lakes, or former lakes, in 

 this country and Europe. They come from the Third 

 river, or Yantacaw, to the Elizabeth river and neighbor- 

 ing streams in north-eastern New Jersey. The bacil- 

 lariacese, sponge spicules and rhizopoda are the same, 

 and grouped together differently but essentially the 

 same. We have five kettle holes (and kettle holes are 

 depressions of the surface mostly exactly circular with- 

 out an opening and dry or with water in them), having 



