258 THE AMERICAN MONTHLY [Aug. 



and also to fix the eye which has a liability to wander. I 

 find in my case I can move one eye without the other, 

 and this makes the image which is formed by tlie right eye 

 move. Of course when the left eye is used to see the pen- 

 cil point tlie prism can be reversed and sometimes it is 

 useful to move it around from the east to the southeast. 

 But these movements can be variable, as can be seen. I 

 wish this camera could be tried, for it is easy to make and 

 easy to use. 



Brackish along with Fresh-water Bacillariaceae. 



By ARTHUR M. EDWARDS, M. D., 



NEWAEK, N. J. 



I have to record again living brackish Bacillariacese 

 along with fresh water ones. And it occurred only a 

 few days ago. One Sunday, in the latter part of June 

 with a bottle in hand, for I never go without one, I was 

 watching the turn of the tide at Bellville, N. J., near the 

 bridge. I saw the water which was coming from a cut 

 off where the Myriophylum and Anacharis was plenty, 

 and snails, Lymnea and Plunorbis in profusion had on 

 the top a dust of Bacillariacese and other things. I saw 

 it go down the river, which is brackish here until it 

 passed to Newark bay a*nd so to the ocean. I wondered 

 what became of those fresh-water forms when they came 

 to the salt water. Did they all dissolve or did they 

 transform into salt-water forms ? I got a bottle full of 

 the water and brought it home and examined it and have 

 it now growing in my window. There was a plenty of 

 Nitzchia obtusa, var. brevissima, A. Gr., Cyclotella striata. 

 Eunotia monodon, Gromphonema turrio, Navicula cuspi- 

 data, Synedra ulna, and various other fresh-water forms 

 but there was living Coscinodiscus excentricus and 

 Surirella striatula. Both of these are put down as brack- 

 ish forms, but I had them here in fresh-water along with 



