AGARDh’s CLASSIFICATION OF ALG2E. 
153 
species of which are natives of Australia and Tasmania ; Eudesme, 
which includes Mesogloia virescens and other species ; Polycerea, 
containing one Tasmanian species only ; Herponema, perhaps only 
a sub-genus of Myrionema, one of the three species of which is 
Elacliista velutina of the Phyc. Brit. Tab. xxvm. ; and 
Caepidium, of which only one species, C. antarcticum , is known. 
This very singular plant is dimorphous. It resembles, as Dr. 
Agardh informs us, in the lower and sterile parts a Riccia ; while 
the upper and fertile parts are like an Anthoceros. The decum- 
bent sterile frond spreads, like a Ralfsia over marine rocks ; but 
the flabellate lobes, instead of being of a scaly form, are almost 
cylindrical ; their ramification intermediate between dichotomous 
and pinnate. The thickened apices of the lobes are round and 
scutate, and on these are formed hollow discs like apothecia. 
From these discs the fertile parts arise. They consist of simple 
filaments about an inch long, as thick as a sparrow’s quill ; the 
lower part is smooth, the upper covered with very minute warts. 
In the substance and blackish colour, as also in the structure 
of the fertile parts, the plant resembles the Chordariese, and Dr. 
Agardh considers that the genus is intermediate between Ralfsia 
and Chordaria, and that its place is amongst the most highly 
developed forms of the Chordarieae. 
As regards the classification of British Algse, important changes 
besides those already mentioned, have been made in the present 
work; Chordaria divaricata and Mesogloia Griffithsiana are re- 
moved to Castagnea ; and Dictyosiphon Hippuroides is, by Dr. 
Agardh, considered as a form of Chordaria Jlagelliformis. The 
reasons for these changes in the classification, which are founded 
on the examination of the structure and fructification of the 
plants, are set forth at length by the author. 
In the preliminary essays on the fructification of the Chordaricse 
and Dicyoteee, Dr. Agardh takes occasion to criticize some 
observations of M. Thuret, published in Le Jobs’ “ Algues 
Marines de Cherbourg,” and in M. Bornet’s “ Etudes Phycolo- 
giques,” relative to the fructification of the Dictyoteae and of some 
of the Chordariese. These remarks by an Algologist so experienced 
as Dr. Agardh will undoubtedly have great weight with British 
students. 
As now constituted, the genus Dictyota contains 26 species, 
several of those formerly included in it being referred in the 
present work to the new genera Dilophus and Glossophora. The 
other genera of which Dr. Agardh treats are Spatoglossum, 
Taonia, Padina, Zonaria, and Haly seris, of all of which the 
fructification has been made the subject of special study in these 
pages. 
The work, which we heartily commend to the attention of 
Algologists, is illustrated with three plates, well executed in mono- 
chrome by Swedish artists. 
11 
M. P. M. 
