INTRODUCTION, ili 
working period for Alge having scarcely commenced, his 
“ Alge Britannicw” appearing in 1830. Jones and Kingston’s 
“ Flora Devoniensis” in 1829 included but 29 species. John- 
ston’s “Flora of Berwick-on-Tweed” in 1831 had 40 species. 
Near this time (1833) Berkeley’s “Gleanings of British 
Algze” was published. The latter volumes of “ The English 
Flora” appeared also in 1833, under the editorship of Sir 
William Hooker, the Alge being contributed by Dr. W. H. 
Harvey, and included 160 species. This was Harvey’s first im- 
portant contribution to the History of British Alge, which was 
succeeded in 1841 by the first Edition of his “ Manual,” con- 
taining 198 fresh water species, Between these two Mackay’s 
“ Flora Hibernica” was issued in 1836, with 87 Irish species. 
These all culminated, in 1845, in the appearance of Hassall’s 
“ Fresh-Water Algew,” enumerating 297 species, exclusive of 
Characee, Desmidiacew, and Diatomacew, thus closing the 
second epoch. The time at which this latter work appeared was 
an active one in British Fresh-Water Algae. Ralfs was preparing 
his work on Desmids, and contributing papers to the scientific 
journals, notably the “Annals of Natural History.” Dr. 
Greville had commenced his “ Scottish Cryptogamic Flora” in 
1823. Harvey was at work earnestly with Marine, and of course 
casually with Fresh-Water Alge. The volume containing the 
Algz of the “‘ English Botany,” second Edition, appeared in 
1844, so that about this time, which we distinguish as the end 
of the second epoch, characterised by the publication of 
Hassall’s work, there was greater promise than came to be rea- 
lized in the early part of the next epoch. 
It is not uncommon to hear observations made disparagingly 
of the work with which the second epoch closed, when no 
account is taken of the difficulties which had to be encountered 
in preparing an illustrated work of that nature. It cannot be 
fair to judge it by its successors, but by its predecessors, and if 
it was fairly up to the general standard at the time of its pro- 
duction, that is all we can expect. It must be remembered that 
Kutzing’s large and splendid work, the ‘‘ Tabula Phycologia,” 
was only commenced in 1846, and that therefore it could not be 
consulted. It is certainly to be regretted that in Hassall no 
indication is given of the measurement of the objects figured, or 
