a 
278 NEMATOGENZ. 
Rivularia echinata. (Znglish Botany.) 
Globose, very minute, dark coloured, compact. Threads 
fastigiate, attenuated upwards to the apex, closely cohering, 
articulated, heterocysts basal, globose. Sheaths very narrow, 
almost inconspicuous. 
Size. Trichomes :007 mm. at base, -25 mm. long. 
Chetophora punctiformis, Kutz. Tab. Phye. iii., p. 4, t. 18, f. 
2. Rabh. Alg. Eur. iii., 386. 
Echinella articulata, Eng. Fl. v., p. 398. Eng. Bot. ii., t. 
2555. Harv. Man. 187. 
Conferva echinata, Eng. Bot. i., t. 1878. 
Conferva echinulata, Gray. Arr. i., 310. 
In lakes, ponds, &c.  * 
This minute species, which was first described and figured in “ English 
Botany,” appears to have been unknown on the Continent. We have 
received it from several localities beside the original one of Ellesmere. 
It is one of the Algze which are associated with the phenomenon called 
“ Breaking of the meres,” thus alluded to by Professor Dickie in his 
“ Botanists’ Guide” (p. 310) :—‘* For some years excursions were made 
with the students of my botanical class to a loch on the estate of Parkhill, 
about four miles north-west from Aberdeen. The sheet of water in 
question is about a quarter of a mile inits greatest length ; on almost all 
sides it is surrounded by extensive deposits of peat, with the soluble 
matter of which a great proportion of the water passing into the loch is 
impregnated. The locality was generally visited in the beginning of 
July ; nothing particular had ever been observed till the summer of 1846, 
when my attention was arrested by a peculiar appearance of the water, 
especially near the edge, but extending also some distance into the loch. 
Numerous minute bodies, with a spherical outline, and varying in size 
from 1-24th to 1-12th of an inch in diameter, were seen floating at different 
depths, and giving the water u peculiar appearance. In some places 
they were very densely congregated, especially in small creeks at the 
edge of the loch. A quantity was collected by filtration through a piece 
of cloth, and, on examination by the microscope, there could be no doubt 
that the production was of avegetable nature, anda species of Rivularia; 
one, however, unknown to me, and not agreeing with the description of 
any species described in works to which I had access. Specimens were 
sent to the Rev. M. J. Berkeley; he informed me that the plant belonged 
to the genus mentioned, and stated it to be Rivdaria echinulata, Eng. 
Bot. Along with it, but in very small quantity, I also found another 
plant, Trichormus flos-aque, Bory. 
“In the first week of July, 1847, the same species were observed 
similarly associated, but the 7richormus was now more plentiful, with- 
out, however, any apparent corresponding diminution in the quantity of 
the Rivvlaria. 
“Jn July, 1848, it was observed that the Rirularia was as rare as the 
Trichormus bad been in 1846; to the latter consequently the water of 
the loch now owed its colour, which was a very dull green; the colour, 
however, becomes brighter when the plant is dried. In neither of the 
seasons mentioned was it in my power to make any observations on the 
colour of the loch earlier or later than the date above mentioned, conse- 
quently nothing can be added respecting the comparative development 
