130 ARCHER, ON PALMOGL@A MACROCOCCA. 
a new and distinct species, though without the conjugative 
state, but which presented to me a very remarkable condition 
not before noticed in this genus. But although thus appa- 
rently rare, I cannot suppose it confined to the following 
form—in other words, 1 would not describe it as distinct on 
that account. I shall defer an account of the condition 
alluded to the general description of the species. 
Mesot#£NIUM MIRIFICUM (mihi, sp. nov.). 
Specific characters.—Cells broadly elliptic; chlorophyll-_ 
plate in edge view very narrow, often curved. 
Habitat.—Like the former, wet rocks, but very rare. 
Locality. Between Loughs Luggelaw (or Tay) and Dan, - 
near Ballinrush. 
General description—Mass pale yellowish-green, gelati- 
nous; cells broadly elliptic; chlorophyll-plate in edge view 
very narrow, excentric, not rapidly attenuated to the extre- 
mities, which are not acute, and do not quite touch the cell- 
wall, often curved ; endochrome dense. 
I have observed the cell-contents bounded by the “ pri- 
mordial utricle”’ escape from the parent-cell without conju- 
gation, through a lateral or terminal or intermediately dis- 
posed opening, effected by the raising up and often separation 
of a lid or valve-like portion of the parent-cell-membrane 
(figs. 22 to 81). During this operation the contents are 
often much constricted, by reason of the narrow orifice 
through which the mass makes an exit. After emergence it 
becomes rounded, and the contents of this resting-spore-like 
body (figs. 24, 25), which do not conjugate or combine with 
any other, become of a reddish-brown hue, with a dark cor- 
puscle in the centre. The empty parent-cell-membrane lies 
hard by, the lid-like structure sometimes apparently still 
adherent by one point—sometimes wholly detached, and 
lying about in various positions, or lost altogether (figs. 22 
to 31). 
What may be the fate of these resting-spore-like bodies I 
cannot say; but to my mind they form an additional reason 
for dissenting from Hicks’ conclusion, already referred to, 
that ‘‘ Palmogloea-forms”’ are any condition of developing 
gonidia of lichens. Somewhat similar spore-like bodies are 
sometimes formed in Zygnema—one such from the entire 
cell-contents of one cell—and they escape from the parent- 
cell through a lateral opening into the surrounding water ; 
