PROCEEDINGS OF SOCIETIES. 121 
title par excellence of the Death-watch, both insects possessing 
the power of producing the ticking sound so well known and so 
like that of a watch. It was generally admitted that the latter 
was the creature to which that sobriquet was originally given. 
Mr. Archer exhibited the, with us, rare Cosmarium moniliforme. 
This species, well marked and very pretty, he had not seen for 
several seasons. He mainly drew attention to it now for the pur- 
pose of pointing out the arrangements of the cell-contents in 
“fillets,” as bearing on his remarks on Cosmariwm curtum (Ralfs), 
at last meeting, especially, as on that occasion he had not a speci- 
men of C. moniliforme to exhibit side by side therewith. This 
plant seems to have a quite similar arrangement of the cell-con- 
tents to C. curtwm, and therefore equally to fall under A. Braun’s 
remarks as to its properly holding a place in the genus Cosmarium 
at all. If, indeed, the very faint constriction of C. curtum would 
nearly shut it out of the genus Cosmarium, what of C. moniliforme, 
in which the constriction is so deep as that the species may be 
best called to mind by conceiving two absolute spheres in contact 
and held together by an isthmus so narrow as to appear reduced 
toaminimum? It may be replied that Plewroteniwm Cosmarioides 
(de Bary) is deeply constricted, and externally a Cosmarium, yet by 
that author it is placed, owing to its parietal chlorophyll-contents 
arranged in bands, side by side with certain Docidia ; therefore 
why not C. curtuwm (Bréb.), Ralfs, (and C. moniliforme (Turp.) 
Ralfs, and C. Ralfsii (Bréb.) too) be separated from Cosmarium ? 
Mr. Archer would not be prepared to argue that they should not, 
nor that the mode of arrangement of the contents, being equally 
constant, may not be equally of value as the outward characters, 
but only to urge that, so long as the genus Penium is characterised 
as it is, without constriction, plants with a constriction should 
not be forced into it. Hence, if it be held that the species here 
adverted to must go out of Cosmarium, there should be a new 
genus, Cosmarium-like as to outward form, and Penium-like as to 
the internal arrangement of the contents. Will observers (de 
Brébisson, Ralfs, Nageli, de Bary, Wallich, Cleve, Grunow, and 
others) agree to this? Mr. Archer would venture to urge 
here, in reply to possible objections, that a question like this, as to 
the generic location of the species alluded to, nor any difference 
of opinion thereon, in no way speaks for the want of permanence 
or individuality of the forms themselves; and the difficulty is not 
that of recognising and identifying forms which constantly present 
the same idiosyncrasies whenever met with, but that of making 
their individual specialities tally with the genera as laid down in 
our books, whose limits may be, perhaps, either too wide or too 
narrow, and whose diagnosis cannot be expected to meet every 
possible contingency. 
Mr. Archer drew attention to a Bulbochete which he could not 
but regard as new, inasmuch as it is not described by Pringsheim 
