1140 Proceedings of Royal Society of Edinburgh. [sess. 
subterranean channels, is conducted to the lake, which is mainly 
nourished in this manner. 
Especially the eastern side of the lake has very many hays, and 
in the lake itself we find many (c. 100) inlets, for instance, the 
wood-covered Sluttness and Geitey ; many of the inlets are craters. 
The small Geitey, although measuring hut 14 kiloms., has no less 
than 10 craters ; the highest of these is 70 feet above the level of the 
lake. Many of the craters are now filled with water, and present 
themselves as circular, quiet crater lakes. 
The vegetation around the lake, upon the inlets and in the lake 
itself, is extremely rich. There exists a list of plants gathered near 
and in Myvatn by Gronlund (1890, p. 107), to which paper I 
refer. The islands are often covered with birch, sorb, and 
willows, the stems of the birch being 12-14 feet high, or with 
Angelica and other plants. 
In the lake itself we find Myriophyllum , Potamogeton, Hip- 
puris , etc., in great abundance. Nostoc is further, according to 
Soemundsson and Thoroddsen, abundant, forming huge masses near 
the shores. Myvatn is an extremely shallow lake ; the oars will 
