G. Gomphonema tenellum, W .Sm . Stipes very short ; F.V. linear,
truncate ; V. lanceolate, extremities slightly produced ; striæ 30 in
•001". Length -0006" to -0014". v.v.
Gomp micropus, Kiitz. Bacill. viii. 12. ad specim. quæ dedit amic. De Brd-
bissou. In Conjugation, Thw. Ann. vol. xx. pi. xxii. fig. n.
Fresh WAter. Wareham, Dorsetshire, Mar. 1848 ; near Lewes, Sept. 18.50,
n . Sm. Near Bristol, J/r. Thwaites. Wray, near Lancaster, Mr. G. Smith.
Cantyre Peat. Marl, Co. Down.
Plate XXIX. 243.
7. Gomphonema capitatum, Ehr. Stipes quite distinct ; F.V. cuneate
; V. slightly attenuated towards the upper extremity, which
is rounded ; much attenuated tow'ards the lower, which is somewhat
acute; striæ 27 i n -001". L e n g th -0009" t o -0014". v.v.
Ehr. Iiif. .xviii. 2. Kiitz. Bacill. xvi. 2.
Fresh water. Lewes, May 18.50, IF. Sm.
Plate XVIII. 237.
8. Gomphonema olivaceum, Ehr. Frustules and stipes forming
mucous masses; F. V. distinctly cuneate; V. slightly attenuated ;
upper extremity rounded, lower acute ; striæ 28 in -001". Length
•0004" to -0018". v.v.
amic. De
Brebisson. Echmellu olimcea, Lyng. Tent. Ixx. c. 1, 2, 3 Gomn
Grev. S. C F. tab^cexliv. 1. ex specim. quæ communicant
cl Auctor. Gomp. Berkeleyi, Ralfs, Ann. vol. xii. pi. xviii. 8. Hass.
Alg. c. 2.
Fresh water : m streams, frequent in winter and spring. River Froome
Feb''Î852 ‘I“ “ ’ ®q"ally abundant;
Mar. 1826 ’ Duddingston Loch, Dr. Greville,
Plate XXIX. 244.
9. Gomphonema intricatum, Kütz. F. V. almost linear, truncate ;
V. lanceolate, obtuse ; striæ 30 in -001". Length -0007" to -0021".
V.V,
Kiitz. Bacill. ix. 4.
Belh^^TaA S u f s ï l ^ ^ ™ ^
Plate XXIX. 241.
10. Gomphonema Vibrio, Ehr. V. almost linear, very slightly attenuated,
obtuse ; striæ 22 in ’OOl". Length -0021" to -0031". v.v.
Ehr. in Kiitz. Bacill. xxix. 75.
Fresh water. Wray near Lancaster, Mr. G. Smith, Aug. 1851. Lough
Mourne and Peterhead Deposits. Marl, Co. Down.
Plate XXVIII. 242.
11. Gomphonema? curvatum, Kütz. Stipes elongated, filamentous
and dichotomous ; F. V. curved ; V. enlarged towards the upper
extremity, which is rounded and inflected, attenuated towards the
low'er, which is acute ; nodules absent in the convex (outer) valve ;
striæ 30 in -001". Length -0007" to -0021". v.v.
/3. Striæ more distinct, 22 in -001".
Kiitz. Bacill. viii. 1. Gomp. minutissimum, Ehr. Inf. xviii. 5. Ralfs, Ann.
vol. xii. pi. ■xviii. 9. Hass. Alg. c. 3. In Conj. Thw. Ann. vol. xx.
pi. xxii. fig. B. Prit. Anim. xiv. 9,10, 11,12 & 17.
Freshwater: ponds, very common. Near Belfast, Aug. 1849; Plumpton,
Sussex, Apr. 1852, TV. Sm. Pond, St. James’s Park, Jan. 1852, Mr. Shadbolt.
Var. ¡3. Shoreham, Kent, 3Ir. Jenner, 1843.
Plate XXIX. 245.
12. Gomphonema ? marinum, I F . Stipes incrassated, branching
in an irregular manner ; F. and V. as in the last species ; striæ 35
in -001". Length ■0005" to -0021". v.v.
Gomp. curvatum, ¡3. marinum, Kiitz. Bacill. viii. 3. Prit. Anim. xvi. 11.
Marine: frequent. Coast of Sussex, Oct. 1851, &c. In Conj. Mar. 1852,
IF. Sm.
Plate XXIX. 246.
The last two species are characterized by several peculiarities. The curved
form of their frustules, and the want of symmetry in the valvular markings
are notable circumstances, which seem to place them apart, while the inflection
of the upper extremity of the valve, easily recognised upon a side view, is a
feature not found in any other species of Gomphonema. The last circumstance
would seem to point to Rhipidophora as their appropriate position ; but the
presence of a central nodule on tbe inner surface, and the more perfectly sih-
ceous nature of the valves, forbid their union with that genus. The species
are so closely allied to each other, that it becomes difficult to distinguish them
by a verbal description, if we confine our attention merely to the frustules ; but
the general appearance of the growing plants, arising from the characters of
their stipes, is very different, and their habitats are so wide apart, that there
can be no doubt of tbeir distinctness.