489 
material of this genus, and as may be seen, in the definition of its 
species I have chiefly followed Le Jolis and Rosenvinge’s opi¬ 
nions. Of several of the forms recorded by authors as distinct 
species, I have certainly found thoroughly typical specimens which 
were easy to determine, but besides these my material contained a 
great many specimens which had characters in common with two 
or three other species, so that it was quite impossible to know 
how to classify them; and by the occurrence of these intermediate 
forms, such an even and continuous series of forms were often re¬ 
presented that I could only regard them as varieties or forms of 
the same species. Having made these introductory remarks, I shall 
now proceed to point out in more detail the reasons which I consider 
most important and on which I have based my definition of species. 
163. E. Linza (L.) J. Ag. Ulva Linza Lyngb., Hydrophyt., p. 32. 
A species fairly rich in forms, the thallus being sometimes 
quite smooth and sometimes having a strongly crisped or undula¬ 
ting surface. Of the forms mentioned by Le Jolis (1. c.), I think 
I have been able to identify more particularly f. undulata and f. 
plana. To unite this characteristic and easily distinguishable spe¬ 
cies with other Enteromorpha species, as Le Jolis does, seems to 
me unjustifiable. 
This species occurs on open sea-shores near low-water mark, 
especially in rock pools, and in sheltered places in shallow water. 
It grows attached to rocks and stones, sometimes also as an epi¬ 
phyte. Fruiting specimens were found in May, June, July, October, 
November. 
This is a common species of the Fseroese coasts where it was first 
found by Lyngbye (1. c.), who writes: — »Ad insulas Faeroenses hie 
illic copiose.« 
164. E. intestinalis (L.) Link. Rosenv. emend., Gronl. Havalg., 
p. 957. 
var. genuina. Rosenv. 1. c. p. 957. Ulva enteromorpha y, intesti¬ 
nalis (L.) Le Jolis, Liste, p. 46. 
The cells in the specimens referred to this variety all have an 
inner wall somewhat thickened which is thickest in the cells at 
the base and then often grows thinner almost imperceptibly in those 
of the upper part of the thallus. I have, however, not met with 
an inner wall as thick as that figured by Ahlner (1. c. f. 16). The 
typical specimens are all branchless and without, or with hardly 
