264 THE AMERICAN MONTHLY [Oct 
perhaps 150 feet long by 50 feet wide, and two or three 
feet deep. Our object in visiting it was to ascertain if 
it contained diatomaceous material; and, while there, I 
made a gathering which, when cleaned up a few days 
afterward, yielded some very interesting slides, and 
some Navicule not previously met with elsewhere. 
The most abundant form in the gathering was Hpithe- 
mia gibba, both the long and the short varieties. The 
most common Navicula was radiosa. Cymbella stomato- 
phora of several sizes was also common; and Amphipleura 
pellucida, a rare form, more than usually abundant. 
My gathering was made on the east side, about midway; 
and it was rather curious that there was no Amphipleura 
in Mr. Patrick’s gathering, made only a short distance 
away at the south end, or from the under sides of the 
leaves of the water-lilies, of which many were growing 
in the pond. Synedra ulna, var. longissima, was abund- 
ant, especially in Mr. Patrick’s gathering. Gomphonema 
was rather rare. There was a considerable number of 
large, somewhat curved, sponge spicules. Naviculacuspi- 
data was a prominent form—both the long and the short 
varieties. Cymbella, usually one of the most abundant 
forms in any gathering East, was very scarce at Gage’s 
pond, as well as Gomphonema. 
The most noticeable thing about the gathering was the 
remarkable predominance of the rare form, Hpithemia 
gibba, of which there were, in a field taken at random, 
under a quarter-inch objective, no less than seventy-eight 
individuals, as compared to nine Cymbella, four Navicula, 
thirteen Syndra, and four Denticula—almost three times 
as many as all the other forms together. 
As some may not have had experience with the micros- 
cope, I would say that the field of view mentioned above 
was round, and one-fiftieth of an inchin diameter. This 
will convey some idea of the exceedingly minute size of 
these diatoms: that 108 of them, as mentioned above, 
gt ee = 
