INTRODUCTION. Ill 



working period for Alga? having scarcely commenced, his 

 " Algas Britannicse " appearing in 1830. Jones and Kingston's 

 te 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 

 Algse "' was published. The latter volumes of " The English 

 Flora' 3 appeared also in 1833, under the editorship of Sir 

 William Hooker, the Alga3 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 Algaa," enumerating 297 species, exclusive of 

 Characese, Desmidiaceaa, and Diatomaceas, thus closing the 

 second epoch. The time at which this latter work appeared was 

 an active one in British Fresh-Water Algse. 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 Algre. The volume containing the 

 Algae of the ' l 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 " Tabulae Phycologias?," 

 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 



