122 ARCHER, ON PALMOGL@A MACROCOCCA. 
(Thwaites). According to Kiitzing, in the former the cells 
are oblong-cylindrical, not, as in the latter, sub-spherical or 
rotundato-elliptic. I before indicated that the latter (C. 
Brébissonii, Thwaites) appears to me far more likely to be 
the same plant as Trichodictyon rupesire (Kiitz.) = Cylindro- 
cystis crassa (De Bary). 
P. macrococca is not the state figured by Hicks of his 
lichen-gonidia; for in the former the cells are oblong-cylin- 
drical, not ovate, setting aside the fact that the latter is 
nothing but what may be called a homomorphic representa- 
tive of that which I am as yet forced to regard as a true 
species. 
I feel satisfied that P. macrococea is not the plant so named 
by Grunow,* of which that writer describes “ the cell-con- 
tents, in certain cases, as exactly like those of Zygnema 
cruciatim, or Desmidium ;” also thata “nucleus, and im each 
cell-half a starch-vesicle, were to be observed.” © Moreover, 
we must infer from the context that his plant occurred sub- 
merged in water. These characters combine in indicating 
that it was not a Mesotenium, but a Cylindrocystis, which 
Grunow must have had under observation—possibly C. Bré- 
bissonii ; but we are without any figure to assist in this de- 
termination. Now, I think there can be no doubt but that 
Palmoglea macrococca is at all events a Mesotenium, and 
not a Cylindrocystis; for those known Palmoglea-forms 
which actually appertain to Cylindrocystis can be best iden- 
tified with forms separately described under other names by 
Kiitzing. 
Since this paper was read I have obtained Rabenhorst’s 
lately published ‘ Cryptogamic Flora of Saxony’ (and adja- 
cent countries). Now, I have here again to remark, with 
every deference, that I cannot concur in considering the 
plant figured by this author as truly P. macrococca (Kiitz.).+ 
Rabenhorst’s figure certainly appears to represent the form 
named Mesotenium violascens by De Bary, and, if it really 
represented the species it is called (P. macrococca), De Bary 
would appear to be right in supposing their actual identity. 
But surely it will be admitted that the narrow cylindrical 
plant represented by Kiitzing is quite a different thing from 
this stout, broadly elliptic form? Yet Rabenhorst describes 
P. violascens separately,t and considers the former (P. 
* © Verhandlungen der k. k. zoologisch-botanischen Gesellschaft in Wien,’ 
1858, p. 489. Grunow, ‘ Die Desmidiaccen und Pediastreen einiger dster- 
reichischen Moore.’ . 
+ ‘ Kryptogamen-Flora von Sachsen,’ &c., 150. 
£ Op. cit., p. 167. 
