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O’Mrara—Report on the Ivish Diatomaceeen ary 239 
NEW YORK 
BOTANICAL 
GARDEN. 
XXX VIT.—Report on tHe Intsu Diatomacrx. By the Rey. Evcrne 
O'Meara, M.A. PartI. (With Plates 26 to 35.) 
[Read June 28, 1875.] 
Ir is now just a century, since in 1773, O. F. Miller discovered the 
first known diatomaceous form; nor was, it till ten years after, the 
same distinguished author was able to add two new forms to the list. 
In the year 1824 Agardh published his ‘‘ Systema Algarum;’’ and 
then the number of species was forty-nine, comprehended under eight 
genera. But if in this province of Natural Science the progress was 
slow during the first half century, it has been very rapid in the last, 
owing not only to the number of eminent labourers in this field of 
research, but also to the greatly improved means of investigation. 
The number of species in Europe alone, as computed by Rabenhorst 
in his index, is about 4000. This may be beyond the mark, but 
certainly Pfitzer is far short of it when he fixes the total number of 
known species at about 1000. It is not necessary to enumerate the 
many authors to whose useful labours the students of this branch of 
Science are indebted, but special notice should be made of Kiitzing, 
who explored the whole surface of the globe; and of Ehrenberg, who, 
not content with the same ample field of investigation, extended 
his researches into the bowels of the earth. But no authors, perhaps, 
have contributed so much to the extent and accuracy of our know- 
ledge, as those who have restricted their labours to some special: 
families, or to the collection and examination of the forms incidental 
to some country or district. The treatise on the Diatomacec of the 
Clyde has earned for Gregory an imperishable name. The Austrian 
forms have been described by Grunow. The Prussian by Schuman. 
The Danish by Heiberg. Those of Sweden and Norway by Cleve, 
and those of Great Britain by Smith in his admirable Synopsis. 
No country would appear more favourable to the growth of these 
forms than our own, with its extensive sea-coast indented with 
numerous bays, its rivers and lakes, and mountain ranges. And yet 
it is strange that Smith, an Irishman, at least labouring professionally 
in Ireland, should haye done but little in exploring its resources, as 
appears from the fact that, in the case of 389 forms figured and 
described by him as British, there are not more than about one 
hundred for which Irish localities have been assigned. Hence it 
might be supposed that the climate of Ireland is not favourable to the 
growth of Diatomaceous forms—an impression which is not justified 
by the fact, as I hope to prove by the present work. 
For many years the intervals of professional engagements had been 
devoted by me to the collection and study of the Irish Diatomacee ; 
and a large amount of material had been gathered and arranged when 
R. I. A. PROC., SER. II., VOL. II., SCIENCE. 2K 
AUG 95 - 1909 
