DIATOMS OBSERVED AT HATFIELD WEST MOOR, 
NEAR DONCASTER. 
J. NEWTON COOMBE, 
ee 
WITH LIST oF pa arte case FOUND. 
¥: NEWTON COOMBE | AND M.'H. STILES. 
Ir the members of the various sections represented at the 
Yorkshire Naturalists’ Union Doncaster excursion, in May last, 
had been able to prolong their explorations on that occasion to 
that many of them would have been rewarded, as I was, by 
results which the labours of a single day, however patient and 
persevering, could not possibly have brought to light. Although 
the list of the Diatomacez published in the programme as 
having being found in the West Moor waters was, thanks to 
Mr. Stiles’ researches, by no means a meagre one, I was pleased 
to be able to confirm his belief that it was far from exhausting 
the number of species of these fascinating shell plants which 
flourish there. I give below the names of Diatoms which I was 
able to identify as occurring at least twice in the samples which 
I examined from about a dozen tubes. 
These gatherings consisted chiefly of flocculent matter which 
the sun’s rays, liberating the oxygen of the Diatoms inhabiting 
it, had caused to rise from the bottoms of the ditches to the 
surface of the niet forming that well-known yellowish-brown 
scum so leasing the eyes of the diatomists. Decaying 
portions of ponte T tates also furnished: good material for the 
habitat of several of the more common species. The letters 
eB and R? placed after sacihe species indicate that it was 
ptt ‘frequent’ or ‘rare’ in the gathering, as the case 
might be. 
The most interesting features in my ‘find’ were (1) the 
number of filaments of A/elosra varians containing megafrustules 
newly formed from the diminutive parent frustule to which they 
were attached, (2) the numerous instances of conjugation taking 
ace among Cyméella cistula Hempr. (NoTE—That, contrary to 
the opinion of Dr. Miquel and other diatomists, conjugation — 
does actually occur in the case of this species, is proved by 
February 1 1899. _ D 
