90 WALKER-ARNOTT, IN REPLY TO DR, DONKIN. 
sentiments are thus expressed (‘ British Desmidiacee,’ Pre- 
face, p. vi): “the name appended to a species merely in- 
dicates the author of the specific name, and has no reference 
to its genus.” But as this would hardly be enough, I am 
compelled, in self-defence, to allude to some antecedents 
with which the public have otherwise no concern. 
Mr. Ralfs, in September, 1857, sent me a slide, prepared 
in balsam, of what he supposed to be ‘ Amphiprora 
didyma” of Smith. In it I did not detect the F.V., 
nor could I observe distinctly the carmation of the valve 
characteristic of Amphiprora; and, m my reply, I gave my 
opinion that it was a Pleurosigma, and, if so, that it might 
prove a broad variety of P. obscurum. In his next letter 
(early in October), he says most justly, that “ the front view 
is very unlike a Pleurosigma,’ and that he was not aware 
of any Pleurosigma having the F.V. constricted, or being 
as broad or broader than the 8.V. In consequence of re- 
ceiving also from Mr. Ralfs some of the material in a tube, 
and being thus enabled to study its F.V. as well as 8.V., 
I readily acknowledged the force of Mr. Ralfs’ objections to 
its being a Pleurosigma. But while I yielded on that point, I 
egaxl not consent to its being 4. didyma, unless Professor 
Ssuitb or the printer had made a great mistake as to the 
strie; and as I understood that Mr. Ralfs was about to 
publish it as an Amphiprora in the forthcoming edition of 
Pritchard’s ‘ Infusoria,’ I proposed to him to allow me to 
name the species after himself. 
The name of the species, therefore, was mine; the merit 
(or, in Dr. Donkin’s estimation, the demerit) of its being 
referred to Amphiprora rested with Mr. Ralfs, and on the 
numerous accurate observations he had made on it when 
recent and in motion. It was not until December, when 
preparing my notice on Rhabdomena for the Journal of 
January, 1858, that, having an opportunity, and wishing to 
obviate the apparent indelicacy of Mr. Ralfs being the first 
to publish the name Ralfsii, I revised the subject with 
greater care, and drew up a diagnosis sufficiently explicit 
for all who are conversant with such topics, and so general 
as to include several forms. Then only could it be said that 
I was responsible for the genus; but, even then, only in the 
same way that Smith is responsible for the genus of Amphi- 
prora alata or constricta, these having been previously 
referred to that genus by others. Dr. Donkin’s remarks 
appeared in the same number of the Journal, and seem to 
have been penned before I myself had formed a decided opinion 
on the point, and at a time when I was no way responsible 
