PROCEEDINGS OF SOCIETIES. 269 
the genus Zygogonium to Kiitzing, Zygogonium (Kiitz.) is not 
the same thing as Zygogonium, de Bary. 
Now there could be almost no doubt, Mr. Archer ventured to 
think, but that the plant now exhibited would fall under the genus 
intended to be established by Prof. de Bary under this name— 
that is, had this distinguished observer been present and asked to 
what genus the plant exhibited should be referred, that he would 
doubtless have replied that it belonged to Zygogonium, as laid 
down in his work. There could not be any doubt but that 
the present, though not the same plant, was at least congeneric 
with de Bary’s. But, on the other hand, if Prof. de Bary be 
correct in his appreciation of the characters of his plant, and in 
his views of the genus founded thereon, Mr. Archer thought the 
present plant could zo¢ fall under Prof. de Bary’s genus as laid 
down by him, that strict attention being paid to the characters 
given by him which is enjoined by a rigid scientific accuracy. In 
other words, assuming the present plant to be really congeneric 
with that examined by de Bary, then his genus must be regarded 
as based on a somewhat erroneous foundation; and, if it should 
be retained at all, it should be so, not for this plant, but for the 
typal form Zygogonium ericetorum, Kiitz., or possibly for some 
others of Kiitzing’s forms in which no conjugation has been seen 
and whose special characteristics, therefore, in this regard, are, of 
course, as yet problematical. 
In order to draw attention, then, to the reason why Mr. 
Archer had formed this opinion and ventured on this statement, 
it would be necessary to give the characters of Zygogonium as 
modified by de Bary, then to describe the plant now exhibited, 
and afterwards to compare it with such diagnosis and endeavour 
to point out its divergencies therefrom, and, finally, to indicate 
what appeared to Mr. Archer to be its proper location. 
The diagnosis of Zygogonium, as given by de Bary (op. cit.), 
is as follows :—‘ Cells cylindrical or barrel-shaped, with thick 
often many-layered cell-wall: towards the middle at each side an 
irregular chlorophyll-corpuscle, furnished with a starch-granule, 
both often confluent into an axile string (in the very thick-walled 
filaments mostly covered with granules). Union of the conju- 
gating filaments ladder-formed. The processes of the two cells of 
the filament which grow opposite one another and take up the 
chlorophyll contents, become cut off as fructification-cells by 
septa, which then become fused together to a non-contracted, 
zygospore.” (‘ Untersuchungen,’ &c., p. 79.) 3 
The type of this genus so defined is supposed to be the 
common Z. ericetorum; but, as it appears, according to de Bary,. 
that the typical Z. ericetorum has not been found conjugated, 
his allusion to the process in the generic diagnosis is founded on 
dried examples, from Professor Rabenhorst’s collection, of a form 
named Z. didymum, which he (Professor de Bary) considers very 
closely to resemble the water-form of Z. ericetorum. 
Now, the plant exhibited by Mr. Archer had short. cells, 
