aLg^:. 
105 
Trochiscia paucispinosa, West . 
T. parva , cellulis solitariis vel in familiis parvis associatis, sub- 
globosis vel leve sub-angularibus ; membrana cellularum crassa, 
aciculis brevibus paucis (periphericis 7-14) ornata. Diam, sine 
acui. 15-17 j \x ; diam, cum acui. 18-20 p ; crass, memb. 1-5-2 p. 
Ben Lawers. 
Analecta Algologica. Observationes de speciebus Algarum minus 
cognitis earumque dispositione. By J. G. Agardh, 
Under this title Dr. J. G. Agardh has issued a reprint of Algo- 
logical papers originally published in the “ Acta. Soc. Physiograph. 
Lund.,” tom. xxviii., and which in form and character may be con- 
sidered a second series, under another title, of the “ Till Algernes 
Syst.” recently concluded. The untiring industry of the veteran 
Algologist, as manifested in his continuous and laborious publica- 
tions, is simply marvellous, and the readiness with which, aided by 
the light thrown by the discovery of new species on existing 
genera, he discards old views and accepts new facts, increases the 
faith with which his opinions are accepted all over the world. 
The natural orders of Algse dealt with in the present treatise 
include the Cryptonemiaceas, Gigartinaceae, Rhodymeniaceac, 
Spheerococcoidise, Chastangiacese, Hypneaceee, Solieriacese, 
Wrangeliacese, and Rhodomelaceac ; a number of new genera 
and species are described and their position is indicated 
by numbers corresponding to those used for the genera in 
the “ Epicrisis Floridearum.” Commencing with the Ceramiaceae 
he divides the genera of the Callithamnieae into two sections 
according to the character of the stem. In the first decurrent 
threads are found inside the cuticle near the base of the stem, and 
in the second the threads are external to the cuticle, and extend 
for some distance. The sub-divisions of these sections are dis- 
tinguished by the nature of the tetraspores, whether cruciate, 
tripartite, or polysporic. 
Dr. Agardh retains as distinct genera Rodochorton, Anti- 
thamnion, Ptilothamnion, Plenosporium, and Halothamnion, and 
confines the genus Callithamnion to plants having tripartite tetra- 
spores, and favellae naked from the beginning, with nuclei in pairs 
or many-lobed, the branching being either pinnate, di- or tri- 
chotomous or alternate, and the stems having no external fibres. 
Callithamnion interruptum is placed in a new genus — Microtham- 
nion — near Rhodochorton, on account of its cruciate tetraspores, 
a position which seems somewhat unnatural. The favellae, how- 
ever, being unknown, its true position is doubtless difficult to 
assign. Antithamnion is made to include eight species, Ptilota (?) 
Hannafordi, Harvey, being among the number. The new genera 
are Platythamnion ( G . heteromorphum , J. Ag.), Acrothamnion (G. 
pulchellum , Harv.), Heterothamnion (G. Muelleri , Sond.), 
Gymnothamnion (G. elegans), Perithamnion (P. ceramioides , 
n. sp. ; P. arbuscula , n. sp., both from Australia, and P. Myurum = 
