PROCEEDINGS OF SOCIETIES. 87 
that author had sought to establish the animal nature of the 
Oscillatoriaceze, and who, by assuming it as a fact, and drawing 
false analogies, seemed to labour under the delusion that he had 
proved his case. It might hardly be imagined that this memoir 
was written so late as the year 1861! 
Mr. Archer likewise exhibited some specimens of a unicellular 
Alga which was referable to Nigeli’s genus Synechococcus, but 
was not, he thought, previously recorded. It is, indeed, to be 
granted that no mode of reproduction, save self-division, having 
been observed in the lower forms of Chroococcacez, their tena- 
bility as species was open to doubt. But the present, as a form 
merely, was even more striking and marked than any described in 
the genus, and therefore not less entitled to a record. Nor did it 
appear to have been described under any other genus or name. 
Kiitzing, had he seen it, would, no doubt, have referred it to his 
genus Palmogloea, as he had seemingly included therein several 
phycochrome-bearing forms along with chlorophyll-bearing plants. 
But none of Kiitzing’s species of Palmogloea.would at all accord 
with the present plant. It had occurred as yet, so far as Mr. 
Archer’s experience, only in one little shallow miniature pool on 
the side of Bray Head. Taken, then, as it stands, this seemed 
an abundantly distinct production. Mr. Archer would first give 
the characters of the genus Synechococcus according to Nagel, 
of which the present plant was a very typical example. Ii¢ is, 
however, to be noted, as Nigeli himself remarks, that the distinc- 
tion between the genera Synechococcus, Gloeothece, and Apha- 
nothece, may possibly not be marked by very absolute characters. 
Family, Chroococcacez. 
Genus, Synechococcus (Nig.). 
Generic characters —Cells elongate, division only in one direc- 
tion, with thin walls, single or united into little families in series. 
Synechococcus erassus, sp. nov.—Cells broadly elliptic, about 
one half longer than broad ; cell-wall very thin. 
This plant is well distinguished from even the largest of Nigeli’s 
species, S. eruginosus, by its still larger size and by its elliptic 
or egg-shaped cells, somewhat narrowing towards the gradually 
rounded ends, not cylindrical, with rotundato-truncate ends. In 
the present plant the cell-wall is very thin, and seemingly without 
any gelatinous investment. It would, Mr. Archer thought, be 
altogether unnecessary, if not, indeed, absurd, to contrast the form 
in question with any other unicellular plant similar in size or 
resembling in shape, containing chlorophyll, such as Penium, 
Cylindrocystis, &c.; and, due regard being had to the generic 
characters, and the form and dimensions of the cells themselves, 
Mr. Archer thought that neither was there any danger whatever 
that the present plant could be confounded with any of the 
related described Chroococcacee. When occurring in sufficient 
quantity on the slide, this plant, presenting, as it does, in a marked 
degree, the characteristic bright «ruginous green colour of phy- 
cochrome, forms an exceedingly pretty object. 
