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Ehr., Die In fu s .; Jennei’, in Flora of Tunbridge Wells,
p. 2 0 6 .
llah. On aquatic plants in ¡)ools and ditches, near Hen-
licld: Air. Borrer. Frequent in Sussex : Air. Jenner.
Cheshunt and neighbourhood: A. II. II. Oswestry :
Rev. T. Salwey. Ilfracombe; Swansea; Dolgelly and
Bangor, North W a le s: Air. Ralfs.
A very distinct little species. The degree of constriction
of the neck varies considerably in different specimens ; and
this circumstance doubtless led to the institution on the part
of Ehrenherg of the Gomphonema capitatum, which is assuredly
bnt a state of G. truncatum.
3. G o m ph o n em a a c u m in a t u m Ehr.
Plate X C IX . Fig. 1.
Char. Fi'ustules in front view cuneate and truncate. Lateral
surfaces constricted, acuminate, striated.
G. minutum Ag., Conspect. Diatom. 1 8 3 2 , p. 3 4 . ; Grev.
in Hook. Br. Flor. vol. ii. p. 4 1 0 . Gomph. acuminatum,
Abhandl. der Akademie d. Wissensch. zu Berlin, 1 8 3 1 ,
p. 86. ; Bericht, der Akademie d. Wissensch. zu Berlin,
1 8 3 6 , p. 5 3 ., 1 8 3 7 , p. 4 4 .; Die Infusor. p. 2 1 7 . t. xviii.
fig. 4 . G. minutum Ealfs, in Annals, vol. xii. p. 4 6 2 .
pi. xviii. f. 5. ; Jenner, in Flora of Tunbridge Wells,
p. 2 0 6 .
Hah. Sussex : Air. Jenner. Cheshunt, &c. : A. H. H.
Ba rmouth: Rev. T. Salwey. Trengwainton ponds,
near Penzance, and pond on Towednack Moor, near St.
Ives ; Dolgelly : Air. Ralfs.
The degree of constriction and acumination of the frustules
would appear to be subject to very considerable variation.
As the species was published at nearly the same period, by
both Agardh and Ehrenberg, and apparently first by Ehren-
berg, I have retained the name of the latter which Is infinitely
the more appropriate.
b. Lateral surfaces not constricted below the apex.
4 . G om ph o n em a c e is t a t u m Ralfs.
Plate C. Fig. 1.
Char. Frustules crested, not constricted below the apex, striated
laterally.
Gomphonema cristatum Ralfs, in Annals, vol. xii. p. 4 6 3 .
pl. xviii. fig. 6 . ; Jenner, in loc. cit. p. 2 0 6 .
Hah. On Conferva glomerata in a stream near Shoreham,
Kent, Dec. 1 8 4 2 . Farnham, Surrey : Mr. Jenner.
The only species with which this beautiful Gomphonema
could be confounded is G. acuminatum, from which it differs
in being altogether a smaller plant, and in the absence of the
constriction below the apex.
Fo r its discovery naturalists are indebted to Mr. Jenner.
5. G o m ph o n em a d ic h o t o m um Kütz.
Plate X C IX . FG. 2.
Char. Frustules linear, cuneate in front view, with very minute
terminal puncta. Lateral surfaces lanceolate, fa in tly
striated.
Kiitz. Synops. Diatom, p. 5 6 9 . fig. 4 8 . ; Ralfs, in Annals,
vol. xii. p. 4 6 3 . pl. xviii. fig. 7. Gomph. gracile Ehr.,
Die Infus. p. 2 1 7 . t. 18. fig. 3 . ; Pritch. Infus. p. 2 2 7 .
G. angustum ? Ag., 1831.
Hab. Trengwainton ponds, near Penzance: ilfr. Ralfs.
The frustules of this species somewhat resemble those of
Gomphonema Rerheleyi, but they are more elongated, narrower,
often nearly linear, and their lateral surface lanceolate,
and not clavate.
6. G om ph o n em a B e e k e l e y i Grev.
Plate C. Fig. 2.
Char. Y xqtA forming large mucous masses. branched,
E E 4
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