1866. ] Botany and Vegetable Physiology. 573 
dium murale, Bupleurwm aristatum, and Vicia sativa. The brick 
contained chopped straw, thus confirming the account of the brick- 
making given i Exodus. The manufacturing relics consisted of 
fragments of burnt tile, pottery, and a small piece of twine spun 
from flax and sheep’s wool, significant of the advance which civil- 
ization had made more than 5,000 years ago. Professor Unger 
thinks that by a careful examination of a large number of bricks, 
much light may be thrown on the civilization of ancient Egypt. 
The bricks also contained abundant remains of fresh-water shells, 
insects, fishes, &e. 
Enexanp.— Discovery of a new British Lemnaceous Plant, 
the Wolffia arrhiza (Wimmer).—Mr. Henry Trimen, M.B., F.LS., 
has given a description of this plant in the August number of the 
‘Journal of Botany.’ It is the smallest of our Phanerogams, and 
was found by Mr. Trimen in a pond near Staines, Middlesex, 
where it grows in abundance, floating on the surface of the water 
between the fronds of Lemna polyrrhiza, L. gibba, and L. minor. 
This minute plant has a very extensive geographical range, being 
found in Portugal, France, Italy, Switzerland, Germany, Bengal, 
Eastern Java, Angola, Egypt, and New Orleans. This species has 
since been detected in the Kew herbarium, dried, amongst samples 
of Lemna minor, and not named. Since the above discovery was 
made, a new station of this plant has been found by Mr. M. 
Mogeridge, in a pool near St. James's Church, Walthamstow, 
Essex. As the Wolffia arrhiza is smaller than a pin’s head, and 
occurs in company with other duck-weeds, it is probable that it 
exists in many other localities, and might be found if such places 
were carefully examined. Dr. Gray, of the British Museum, 
thinks that this plant is not a recent importation to England, as 
about 50 years ago Mr. Bennett and himself had some specimens 
of it brought to them by M. Gerard, which were found on Putney 
Common. M. Gerard maintained that it was Lemna arrhiza, but 
Dr. Gray thought at the time that “it was only a young state of 
Lemna minor, for the difference between the fructification of the 
two plants had not been then described.”* 
The Lemnaceze of British India have also been described by 
Mr. Sulpiz Kurze, Curator of the Herbarium of the Royal Botanical 
Gardens, Calcutta. Seven species are enumerated, two of which 
are new, and, so far as at present is known, restricted to India, wz. 
Wolffia microscopica, Kurz., and Lemna oligorrhiza, Kurz. Duck- 
weeds, therefore, occur nearly as generally in the tropics as m 
northern countries, though a moist region, covered with tanks and 
rivers, is more favourable to them than a dry one. Bengal 1s rich, 
not only in species, but in the number of individuals. As to the 
* See ‘ Journal of Botany,’ August, 1866. 
20a 2 
