Greville^ on New Diatoms. 
15 
Hab. Port Jackson^ New South Wales ; Dr. Roberts. 
In a mounted slide presented to me hy Dr. Roberts I find 
the beautiful Campylodiscus now described. In the dry pre- 
paration the valve is of a dark-blue colour. The canaliculi 
are fine and sharp, and the separation between the marginal 
band and the central space is marked by a very narrow blank 
line. The ridge which runs along the middle of the band of 
canaliculi is so prominent that, at first sight, there appears to 
be a solution in the continuity of the canaliculi, which, how- 
ever, is not the case. The costse in the centre are not in the 
slightest degree moniliform. It is a robust species for its size. 
Navicula Lewisiana, n. sp., Grev. — Valve elongated, linear 
oblong; strise very fine, parallel; median line terminating 
considerably within the apices in a linear, elongated nodule, 
the base of which rests in a socket. Length -0076" to '0122". 
Navicula, n. sp. ? or sporangium of N, rhomboides ? Lewis, 
'Notes of Diatom, of the U.S. Seaboard,^ p. 6, pi. ii, fig. 3. 
Navicula, n. sp. ? or sporangium of N. rhomboides ? or N, 
fossiliSj Ehr. Lewis, in ^Mic. Journ.,^ n. ser., vol. ii, p. 161. 
Hab. India (Sunderbunds) ; Dr. Wallich. Mud from 
oysters, St. Mary^s River, U.S. ; tidal mud from Savannah 
River, U.S. ; marsh at Pernandina, Florida ; Dr. F. W. Lewis. 
Mouth of the River Berbice ; Dr. Abercrombie. Sierra Leone, 
in gathering communicated by Frederick Kitton, Esq. 
Of this diatom Dr. Lewis remarks that it is nearly allied 
to Nav. rhomboides and crassinervia, more particularly to var. 
j3 of the first named, and, perhaps, notwithstanding its marine 
habitat, ought to be regarded as a variety of one or other of 
these species.^' Dr. Lewis, however, at the same time re- 
gisters it as a doubtful new species, and I am myself certainly 
disposed to consider it as really distinct. With regard to 
mere figure, the frustules of both Nav. rhomboides and crassi- 
nervia are decidedly lanceolate, whereas those of the diatom 
now before us have the sides nearly parallel at the middle, 
and although gradually narrowing as they approach the apex, 
are still, at that part, broadly rounded. And I am not aware 
that we have any authority for assuming that the sporangial 
condition would cause so radical a change in the frustular 
form. In the absence of any such evidence, it appears 
to be a safer proceeding to treat it as new. But the diff'er- 
ence in form is, indeed, the least argument in favour of such 
a conclusion. The terminal nodules alone constitute an 
essential peculiarity. They are situated at a considerable 
distance from the apices, are elongated, apparently cylindrical, 
and are, besides, connected in so curious a manner with the 
