2 
RoPER^ on Biddulphia. 
The late Professor Smithy by extensive research and consi- 
derable judgment, has placed our native species of Diatoma- 
cese on a tolerably sound foundation, as compared with the 
overloaded classification of previous observers; and by 
generally characteristic generic descriptions, aided by the ad- 
mirable figures of Mr. TufFen West, has enabled every 
careful microscopic observer to study these interesting forms 
of life with comparative confidence. But, as the limits of 
his work would not permit him to enter largely into the cha- 
racters of any particular genus, and, at the same time, those 
from foreign habitats are altogether unnoticed, I pro- 
pose, in the present communication, to bring before the 
Society as complete a monograph as the means at my dis- 
posal will admit of the entire genus of Biddulphia, and, 
having referred to all the authorities, to form a synonymy 
which will bring it into a more intelligible form than at pre- 
sent exists. 
Professor Smith I consider has acted with sound discrimina- 
tion, in again uniting the genera Zygoceros, Odontella, Denti- 
cella, andCerataulusof Ehrenberg and Kutzing, under the head 
of Biddulphia ; and v»^hilst I propose to adopt the arrangement 
so far, as brought forward in his ^ Synopsis,' I wish to bring 
before the Society my reasons for dissenting from some 
points in his classification, which I think it very probable he 
would have been inclined to modify, or partially rearrange, 
from evidence that has lately been discovered, had he lived 
to bring out another edition. 
The earliest notice of the genus Biddulphia is that in 
Smith's ^English Botany,' dated in 1807, where it is alluded 
to, under the name of Conferva Biddulphianum, as " a curious 
plant, of which we find no description, found by Miss Susan 
Biddulph, in November or December last, at Southampton." 
The figures, however, given in the plate. No. 1762, although 
said to be exact copies of chosen specimens," are drawn 
apparently from difPerent plants; the upper figures alone 
being those of Biddulphia, and though small and rather 
roughly drawn, are evidently taken from specimens of 
B. pulchella. Dillwyn, the next writer who notices it, in his 
*■ British Confervse,' published in 1809, merely repeats the 
statements in the ^ English Botany,' but does not appear to 
have seen the plant, and gives no figures. Lyngbye, in his 
' Tentamen Hydrophytologise Danicse,' published in 1819 — 
a surprising work for the extent of research and accuracy of 
his delineations, considering the little attention then paid to 
microscopic subjects, and the inferiority of his instruments to 
those now in use — appears not to have met with B. pulchella ; 
but he describes and figures, as Diatoma auritum^ another 
