199 
THE CHARACTER AND DISTRIBUTION OF 
THE DIATOMACEA., 
By B TAYLOR, 
(Read at Whitehaven. ) 
TueE Diatomacez consist of a large tribe of one-celled organisms, 
found in greatest abundance during the first and last three months 
of the year. They are met with abundantly in the shallower parts 
of fresh, salt, and brackish water. They grow on mud, stones, 
sea-weed, shells, zoophytes, submerged timber in tidal harbours, 
and on the bottoms of vessels that have been long afloat. They 
may also be obtained just now (September) in boggy ground, and 
on the various mosses that clothe rocky cliffs and brows down 
which water trickles. As examples of some of these habitats, I 
may refer to the mud of our Harbour, which a few weeks ago was 
thickly covered with great numbers of Pleurosigma angulatum, 
Surerella gemmo, P. asurii, and Stauroneis salina. On the Rifle- 
range, in the corner of the angle formed by the rocks and the 
target bank, is a small piece of boggy ground where they may be 
obtained in enormous quantities. Another locality rich in diatoms 
is the short piece of dripping rock that skirts the New Road a 
few yards beyond the Wheelbarrow Brow. 
The Diatomacez owe their name to the readiness with which 
those members of the class which grow in filaments, or aggregated 
masses, break up on the slightest touch. Their common English 
name, Brittlewort, is also equally expressive and descriptive of the 
same property. This quality of brittleness is owing to the presence 
