490 
any prolifications; forma cornucopice was first recorded by Lyng- 
bye under the name of Scytosiphon intestinalis f. cornucopice , Hy- 
drophyt., p. 67. 
var. micrococca (Kutz.) Rosenv. 1. c. p. 957; Ulva enteromorpha y, 
intestinalis ? h, micrococca Le Jobs, Liste p. 47; Enteromorpha saxi- 
cola Simmons, Meeresalg., p. 272. 
Of this variety, I have found several quite typical specimens, 
e. g. corresponding exactly to Ahlner’s description of Enteromorpha 
micrococca (1. c. p. 45). The specimens were small, 3—4 cm. in 
length, often somewhat prolific, or branching. The cells were small, 
3—5ju broad, and had in the transverse section an especially thick 
inner wall so that the thallus was nearly 18 -20 g thick. From 
these typical specimens, the transition might be traced by quite 
easy stages to the different varieties mentioned in the following, 
such as var. genuina and var. minima. Thus, many specimens 
were found, in which the cells were becoming by almost imper¬ 
ceptible degrees larger, and the walls thinner, until they merged 
quite evenly into var. minima. In other larger specimens, the cells 
too became larger, thus forming an easy transition to var. genuina. 
The rather considerable material at my disposal has shown 
me conclusively how much the inner wall af typical E. micrococca 
really varies in thickness. I have found the easiest transition be¬ 
tween specimens in which the inner wall was thick and others in 
which both the walls were of the same thickness, and others again 
in which the outer wall was the thickest; the latter character pro¬ 
bably induced Simmons to separate off' the new species E. saxicola; 
but my researches prove, as is no doubt sufficiently clear from the 
preceding remarks, that the species E. saxicola cannot be main¬ 
tained. To explain this more fully I may add that it is not only 
between the different specimens that such transitions occur, but 
even in the same individual very often something similar may be 
observed. A transverse section of the thallus shows, e. g., that the 
outer and inner walls of the cell of the lowest part of the plant 
are often almost of the same thickness; in the upper part only the 
inner wall is specially thickened, while at the top it may happen 
that neither wall shows any noticeable degree of thickness. I ob¬ 
served something quite similar in the original specimen of E. saxi¬ 
cola , in which even if the outer wall is sometimes thicker than the 
inner, the reverse is also often the case. 
var. minima (Nseg.) Rosenv. 1. c. p. 959. 
