i - ■! » ■:
11. Epithemia Musculus, Kütz. V. regularly and highly arcuate,
extremities acute ; canaliculi distant ; striæ 40 in -001". v.v.
Kütz. Bacill. XXX. 6.
Brackish water. Poole Bay. “ Little Sea,” Dorsetshire, Aug. 1848. Near
Lewes, Sussex, Sept. 1850, IF. Sm.
Plate I. 10.
12. Epithemia Westermanii, Kiitz. F. V. elliptical ; V. arcuate;
canaliculi distinct; striæ faint, 40 in -001". Length -0008" to
•0013". v.v.
Kütz. Bacill. V. 12? Eunotia JFestermanii, Ehr. Inf. p. 190. taf. xiv. 6 ?
Brackish water. Near Lewes, Oct. 1850, TF. Sm. (Ceylon, Mr. Thwaites,
Nov. 1851.)
Plate I. 11.
13. Epithemia rupestris, n. sp. F. V. elliptical-lanceolate ; V.
acute, slightly arcuate ; canaliculi distant, 6 in -001" ; striæ faint,
42 in -001". Length -0012" to -0023". v.v.
Fresh water. Backsbottom near Lancaster, Mr. G. Smith, April 1851.
Plumpton, Sussex, April 1852, W. Sm. Aberdeenshire, Dr. Dickie. Killi-
crankie, Mr. P. Grant, Kaasay Earth.
Plate I. 12.
The above species first fell under my notice in a gathering made by Mr. G.
Smith from the surface of a rock moistened with water in the habitat I have
mentioned ; its frequent occurrence in other localities shows that it is widely
distributed in subalpine districts. Together with the species last described,
and the three which follow, its valves present a peculiar form : their convexity
is so considerable, that a transverse section of the frustule would furnish an
outline not unlike the figure 8, owing to which circumstance a side view is with
difficulty obtained, the frustules naturally presenting their broadest surface to
the eye.
14. Epithemia constricta, n. sp. F. V. elliptical with a more or
less distinct constriction ; V. acute, much arched ; canaliculi distant,
8 i n -001" ; striæ 30 i n -001". L e n g th -0012" t o -0026". v.v.
"Ep. constricta,” cl. De Brebisson in litt. cum specim.
Brackish water. Excet, Sussex, March 1852, W. Sm.
Supp. Plate XXX. 248.
15. Epithemia gibba, Kütz. F. V. linear, slightly inflated at centre
and extremities; S. V. linear, obtuse ; striæ 36 i n -001" ; canaliculi
15 in -001". Length -0033" to -0104". v.v.
Nav. cjiUa, Ehr. Inf. xiii. 19. Hass. Alg. cii. 4.
Ep. gibba, Kiitz. Bacill. iv. 22.
Eunotia gibba. Prit. Anim. xv. 27. In Conjugation, Thw. Ann. vol. xx.
pi. xxii. F.
Fresh water : frequently entangled in the mucus of Sorospora virescens,
Hass. Wareham, Aug. 1847. Lewes, Oct. 1850, W. Sm. Lough Mourne
Deposit. Peterhead ditto. Near Aberdeen, Dr. Diche. Rescobie, Mr. I .
Grant. (San Fiore, Italy; Ceylon, 1851, Mr. Thwaites:)
Plate I. 13.
16. Epithemia ventricosa, Kütz. F. V. elliptical, slightly constricted
at the ends ; V. with acute extremities ; striæ and canaliculi
as in the last. Length -0009" to -0018". v.v.
Kütz. Bacill. XXX. 9. Nav. gibba, Ehr. Inf. taf. xhi. fig. xix. 4.
Fresh or brackish water. “ Brooks ” near Lewes, Oct. 1850. St. Ouen’s
Pond, Jersey, Aug. 1852, W. Sm. Near Aberdeen and near Belfast, Dr.
Dickie. Peterhead Deposit.
Plate I. 14.
G e n u s 2 . EUNOTIA, Ehr.
Frustules free, oblong; valves arcuate, with terminal nodules and
convergent striæ.
Closely allied to the former genus, but easily distinguished by the
absence of canaliculi, the delicacy of the striæ and the dorsal ridges
with which most of the species are provided. The F. V. is also uniformly
linear, and the connecting membrane less fully developed than
in many of the Epithemiæ. Isolated frustules of Himantidium might
be confounded with the present species, but Eunotia never forms a
tenacious filament, though several frustules may sometimes be found
united ; the genera are however closely allied, and with difficulty
distinguished from each other.
1 . Eunotia Arcus, W. Sm. V. regularly arcuate, acute, with a
.slight constriction at each extremity, and inflation in the centre of