to me by Mr. Ralfs as #. percursa, but which our friend Mr. 
Thwaites decided to belong to a different species. In the pre- 
sent figure I hope I have given the true plant, but not having 
had the advantage of examining any authentically-named spe- 
cimens, I am obliged to trust to the general accordance of the 
specimens here figured with the description given by Carmi- 
chael. My figure is drawn from a specimen collected by Miss 
Ball some years ago at Clontarf, and now in Herb. T. C. D., and 
it sufficiently accords with such specimens as I have examined 
from other parts of the coast. Ifthe threads were all of one 
diameter, and all built of a double row of cells, there could be 
no difficulty in ascertaining the identity of the species; but 
unfortunately this is far from being the case in any specimen I 
have seen. The character by which £. Ra/fsiz differs is, the 
large size of the cells and the minuteness of the grain of endo- 
chrome in each. ‘This, in the specimens seen, is very obvious. 
How far it may be of specific importance I cannot say. 
Fig. 1. ENTERomMorPHA PERCURSA :—the natural size. 2. Portions of fila- 
ments of various sizes :—highly magnified. 
