bianctte. alae DPCM ihr ay oes a 
THE ALGA-FLORA OF CAMBRIDGESHIRE. 51 
recent years, and since the publication of the latest English 
text- —- the classification of the freshwater alge has changed 
very greatly. Many of the old orders and families, founded on merely 
transitory or conditional characters, have had to be abolished, and 
a state more or less of chaos has had to be reduced and consolidated 
into what may now be fairly salaienba to be the foundation of a 
natural dene In the Chlorophycee many of the genera con- 
sidered: at one time as doubtfully distinct have been proved either 
to be te or identi with others. Hormiscia and Ulothrix have 
been united under the first-named genus, Glwocystis and Chloro- 
C 
coccum under eae and the characters which constituted the 
genera Mougeotia, Mesocarpus, ee Plagiospermum, and 
Craterospermum have all been fo o be present in one species.* 
Wille’s discovery of the occurrence ve ris nia and antheridia in 
Cylindrocapsat has necessitated the removal of this plant from the 
Palm ze to a new order—Cylindrocapsaces—in close proximity 
to the Cidogoniacee ; and the discovery of sexual organs in Aphano- 
chete{ also requires a transference of — genus from the Cheto- 
phorew to the Coleochetaceew. The energetic investigations 
Prof. G. von Lagerheim and others have shown that man 
Protococcace, a ch were regarded at one time as doubifally 
distinct and in consequence relegated by Bennett and Murray§ 
the ‘‘ Protophyta,’’ are really distinct — soaibened "of a 
complete, if simple, life- history of their 
Bornet and Flahault’s Revision des Nastocaodes Heterocystées|| and 
Gomont’s Monographie des Oscillariées,41 two splendid works the 
value of which cannot be over- estimated, have put the filamentous 
Myxophycew in a new aspect, but the Ghationcsenses et remains 
in a state of considerable confusion. ‘The comparative neglect of 
this order by many algologists is clearly shown by the fact that in 
The Freshwater Alga of the United States, by the late Rev. Francis 
Wolle, it occupies only eleven out of a total of 839 pages. An 
ros aa of rae may be a are from the following passage 
ted fro: On p. 330 he says :—‘‘It is now clearly 
peal that all of these so-called maioeliaiat plants constitute 
nothing more or less than conditions in the = li = of higher 
forms.’’ I maintain that this statement is by no means proven. 
As is well known, those habitats in which Chro eohanndiia plants 
mainly flourish are those which also furnish a prolific growth of man 
Nostocee, oerpapenintd rte Sirosiphoniaces ; but, does the fact 
of association together and their ability to live only under the 
same conditions of eavironinehh necessitate that they should 
* Mougeotia calcarea he ‘Om eg och Ol. Sédtv.-Alg.,’ Bih. till K. Sv. 
Vet.-Akad. Handl. Bd. 1, n 40-42, 
t Wille in Warming, Handbag i cee Syst. Botan 
t apes ‘Sur l’Aphanochete —. et ag isiiodcisbiots sexuée,’ Bull. Soe. 
Bot. Fr. t m. xii, Sess. extraord. p. xciv. 
§ A. W. Bennett & G. Murray, 4 iat of Cryptogamice Botany. 
|| Ann. des Sci. Nat. 1886-8, 7e série, iii.vii. 
‘| L.c. 1892, Te série, xv.-xvi. 
E 2 
