108 
ther, and Micrasterias is separated from Euastriim^ 
but on the contrary Euastriim and some Xanthidia 
are connected with Cosmarhim. Later authors have 
eliminated from the family 6 of his 12 genera, al¬ 
though they also included species of true Desmids. 
i 
In ”the British Desmidieæ” of Ralfs 1848 all 
the British forms are described in detail and excel¬ 
lently figured, and in an ”Appendix” he added a list 
of species not hitherto detected in Britain with shorter 
descriptions and figures of a great number of these. 
It therefore became a monograph of the family. 
From the works of the authors before Ralfs it 
can be seen that several papers of their predecessors 
had been inaccessible to them, especially as the Des¬ 
mids have been claimed both by zoologists and bota¬ 
nists. Times of war and difficulties of communication 
were conducive to such a result. Ralfs also complains 
and says he was: ”at a distance from the metropolis 
and without access to many works which it would 
have been desiderable to consult. Amongst these I 
have more especially to regret that I have not seen 
some valuable papers on the Desmids by Ehrenberg, 
Corda, and Morren, which have been published in 
various foreign periodicals.” We have found that the 
following species of Corda, Ehrenberg, Focke and 
Kützing are not quoted or described in Ralfs" 
British Desmids: 
Corda 1829 in Sturms Deutschl. Flora II. 18 
t. 14: Echinella Lima ~ Clost. Leihleinii Kütz.?; t. 
16: EcJi, fusiformis = dost, spec.? 
Corda in Alim, de Carlsb. 1835: Cosmarium 
bipes^ afterwards by Ehrenberg identified with Cos¬ 
marium Botrytis. — Cosni. stellinum^ by Ehrenberg 
quoted under Eti. Bota {Mier. rotata). — Colpopielta 
viridis., by Ehren berg with ? 1836 with Eu. Iceve 
and 1838 with Eu. integerrimum united; by Brébisson 
