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paper in the shade are of a dull yellowish green ; but if these 
be now exposed to the direct rays of the sun, for about ten 
minutes, they will be found to have assumed a bright bluish 
green, which they do not again lose. 
During decomposition in water a fluid is produced, which 
is of a claret red under reflected light, but of a fine grass-green 
when viewed by transmitted light. 
Dr. Allman also read a notice of a species of Peridinea, 
which had just shown itself in such inconceivable multitudes 
as to give rise to a peculiar coloration of some of the ponds in 
the Phcenix Park. During the last three weeks a spectator 
on the banks of the large ponds in the Park must have been: 
struck by a brown colour assumed by the water. This colour 
was sometimes uniformly diffused through the water ; at other 
times it appeared as dense clouds, varying from a few square 
yards to upwards of 100 in extent. 
A microscopic examination of the water proved the brown 
colour to be entirely due to the presence of a minute organism, 
which the author preferred referring to the genus Peridinea, 
Ehr., rather than constructing for it anew one, though it does 
not exactly agree with any published generic description. 
ss 1 
It is about the ana 
in form to a sphere divided by a deep annular furrow into two 
hemispheres, on one of which is situated another furrow, spring- 
th of an inch in diameter, and approaches 
ing vertically from the annular furrow, and terminating at the 
pole. The author viewed the organism under consideration as 
essentially a solitary cell; it encloses reddish-brown granular 
contents, and a large, well-defined central nucleus. In the 
midst of the contents are numerous clear spaces, of various 
sizes, which, however, appear to be oil-drops rather than true 
vacuole. 
In most instances a deeper-coloured ocelliform spot was 
evident near the polar extremity of the vertical furrow. 
