Edwards^ on DiatomacecB. 
91 
Pleurosigma nubecula. 
„ strigosum. 
„ intermedium. 
Surirella striatula. 
„ salina. 
ovata. 
Tryblionella scutellum. 
„ punctatum, 
„ ang'ustata. 
Triceratium alternans. 
„ favus. 
undulatum. 
Mastogloia lanceolata. 
RhabdoHema arcuatum. 
Stauroneis salina. 
Synedra vertebra. 
Surirella splendida. 
linearis, 
angusta. 
Brightwellii. 
A few more might be added to this list^ but I have 
not determined whether they are new or varieties of old 
species. The mixture of marine and fresh- water forms at 
this locality is curious^ and most likely results from springs 
that open into the marshy and from the washings of the hills 
at the back of it. The Doryphora amphiceros at this locality 
exhibits a great variety of outline^ and plainly shows that 
Smith was right in classing them all under one species. 
Navicula maxima occurs as the ordinary form^ and of the same 
length but about half the width_, together with an inter- 
mediate form. Navicula didyma occurs of two distinct 
forms, and yet they are evidently the same species. One 
is the ordinary form, with the somewhat oval ends ; and the 
other has a much deeper constriction at the middle, and the 
ends are of the form of the ace of spades. Otherwise, that 
is to say in length, markings, &c., this form is the same as 
the normal type. The N. maculata of this list is synonymous 
with Bailey^s Btauroneis maculata, which is evidently a 
Navicula. The N. permagna is Bailey^s Pinnularia permagnaj 
which should also be placed in this genus. Of Pleurosigma 
intermedium I have seen only one or two specimens, and they 
had a peculiar double flexure in the median line, which near 
the central nodule was bent the opposite way to that at the 
ends. 
If the above remarks are found worthy of acceptance, I will 
with pleasure add a few remarks on some fresh-water gather- 
ings in the United States. 
The Annual Soiree was held May 5th, at the South 
Kensington Museum, when 3000 persons attended. 
