NOTES—ORIGINAL AND SELECTED.
143
week in May, the animals died off rapidly, and with the de-
composition of the body the eggs were liberated. The writer
has noticed that isolated individuals containing large numbers
of eggs never deposit them while alive. The algal cells set
free on the death of the worm continued to live, and
developed an investing membrane and passed into a resting
stage, probably awaiting an opportunity of invading the next
generation of Dalyellia.
Prof. Sekera thinks that the alga is of little or no value to
the worm by way of providing food, his reasons being that closely
allied species living under similar conditions do not contain
algae, and that solid food is ingested after the algal cells are
fully developed.
Sir J. G. Dalyell wrote an account of this interesting species
in 1814, and states that it sometimes occurs in large numbers,
and then disappears suddenly. He found his specimens chiefly
in the spring, but some were found in autumn.
Von Graff in his Monograph on the Turbellaria gives a list of
24 species living in fresh water which are frequently associated
with algal cells.
An interesting description of the association of algal cells
with a marine Turbellarian worm (Convoluta roscoffiensis) is
given by Keeble in his little book on Plant Animals. In this
case, however, true symbiosis is undoubted, as the animal ab-
stains from solid food when in an adult state, and digests the
products assimilated by the alga.—H. Whitehead, B.Sc.,
Essex Museum of Natural History, Stratford.
BOTANY.
Lathyrus tuberosus L. at Buckhurst Hill.—The Fyfield
Pea has appeared during the last two summers as a "casual"
upon the railway embankment of the loop line between Woodford
and Chigwell, in the parish of Buckhurst Hill, between there
and the river Roding. Several plants, covering a square yard of
surface, and possibly all originated from a single tuber, were
found by Mr. Howard growing amongst the clinker ballast thrown
down upon the embankment, and an unmistakable specimen
was (September 1912) brought to me for specific confirmation.
The railway embankment in question has proved a rich ground
for "casuals" for years past, but the present record, by which