10 
him this year, and a very rare moth, Deiopeia pulchella (crimson 
speckled footman), taken by him on September the 4th, at Hove. It was 
in such beautiful condition as to favour the idea of its being bred in this 
country. Mr. Wonfor mentioned that, on the last occasion when it 
appeared near Brighton, two were taken; and, curiously enough, 
another was taken on the Race Hill on September 11th, somewhat 
rubbed, by Mr. Gorringe, of Richmond-buildings. 
SEPTEMBER 28TH. 
MICROSCOPICAL MEETING.—MR. WONFOR ON 
“ DIATOMS.” 
Mr. Wonror remarked that he introduced his subject for the 
evening, ‘‘Diatoms,” with some diffidence in the presence of some, 
especially of Mr Hennah, who had devoted much time to their-study 
and who knew a great deal more about them than he did. 
Diatoms, were unicellular algze of a peculiar character, distin- 
guished from other unicellular plants, and especially the Desmids, with 
which they had a great affinity, by the possession of a siliceous cover- 
ing, which, while it rendered them exceedingly brittle—hence their 
name brittle-worts—also rendered them all but indestructible under 
ordinary circumstances. One great peculiarity was the fact that if the 
internal cell membrane became exposed to water, it secreted a 
siliceous covering ; if the plates or valves forming the frustule even 
became separated, a plate of silex began to form and became what was 
termed the connecting membrane. The frustules were either free— 
4.e.—moved freely in the element in which they were found, from 
which circumstance they had been designated animals, adherent or attach- 
ed to the substances on which they grew or aggregated ; in this last case, 
they cohered either by their angles, were provided with a gelatinous 
pedicel which united the frustules together, or they were enclosed in 
great numbers in a general thallus. 
The separate frustules, when seen from a front or side view, pre- 
