1124 Proceedings of Royal Society of Edinburgh. [sess. 
Schroder (1898, p. 529) has measured a form of R. erie 7 tsis, 
Avhich he found near Breslau ; this form is shorter than ours. 
K. M. Levander* (1904) has recently written a little paper on 
the Rhizosolenias of Finland ; he has found R. eriensis in two 
lakes, and has had specimens from Lake Erie for comparison ; his 
drawings of the Finland as well as of the Erie forms agree well 
with my drawings. 
Table YI. 
Saxony. 
Breslau. 
Finland 
(Keitele). 
Finland 
(Valijarvi). 
Iceland 
(Thirigvalla- 
vatn). 
Canada. 
Recorded by, 
O. Zacharias 
B. Schroder 
Levander 
Levander 
Ostenfeld 
Levander 
M 
M 
M- 
V- 
Length of the setae, 
20-40 
18-7-25-5 
24 
40 
14-24 
25-40 
Length of the cell 
without setae, 
30-64 
30-57 8 
52 
80 
68-136 
70 
1 Breadth of the cell, 
6-10 
9-4-15-3 
11 
12 
8-16 
12-20 
In Table YI. I have placed the different measurements together ; 
it will be seen that the Icelandic form is somewhat longer than 
the others, but has shorter setae. 
The narrow race seems also to have been found by 0. Zacharias, 
and his drawing and notes are published as quoted above. In 
1898 he has named it R. paludosa, Zacharias, but in 1899, p. 87, 
he has taken it as a variety of R. longiseta, Zacharias, formerly 
described by him. From this species it differs by the much 
shorter setae, the curved shape and the more distinct structure ; the 
cells with setae are 100 to 120 g long, and 8 to 12 g broad, while 
the setae are about 40 p. The typical R. longiseta , Zacharias, has a 
length of 160 p (without setae) and the setae measure about 180 to 
200 p. By these figures it becomes evident that there is a great 
difference between the type and the variety, and if we take the 
narrow Icelandic form as belonging to the variety, the difference 
will be still greater. Although the above-mentioned measure- 
ments of the Icelandic form in some ways differ from Zacharias’ 
figures of his R. paludosa , I have found it better to register my 
* I have taken the figures of the Erie form in my Table YI. from the drawing 
on his plate i. 
