í V
the concave margin; striæ delicate, 3G in -OOl". Length '0012"
to -0029". v.v.
Navicula Arem, Ehr. Inf. xxi. 10. Cymhellal Arcus, Ilass. Alg. c. 6. Ce-
ratoneis Arcus, Kiitz. Bacill. vi. 10.
Fresh water. In boggy pools, Dorsetshire, Jan. 1849, W. Sm. Wray
near Lancaster, Jan. 1852, Mr. Geo. Smith. Mountains in Forfarshire, Dr.
Dickie.
Plate II. 15. Frustules with endochrome. Frontispiece, v. i. fig. XV.
2. Eunotia gracilis, n. sp. V. arcuate, extremities recurved ; striæ
delicate, 42 in -00]". Length -0006" to -0018". v.v.
Fresh water. AVareham, Sept. 1849, ÍF. Jack’s AVood Spring, Tunbridge
AVells, Mr. E. Jenner. ‘ ®
Supp. Plate XXX. 249.
3. Eunotia monodon, Ehr. V. regularly arcuate, obtuse, extremities
slightly produced ; striæ 34 i n -001". v.s.
Ralfs, Ann. vol. xiii. pi. xiv. 1.
Fresh water. Ben M" Dhui, at an elevation of 3000 feet, Mr. P. Grant
Aberdeenshire, Dr. Dickie.
Plate II. 16.
4. Eunotia diodon, Ehr. V. with two dorsal ridges ; striæ 32 in
•001". v.s.
Ehr. Inf. xxi. 23. Ralfs, Ann. vol. xiii. pi. xiv. 2. Hass. Alg. xcvii. 0.
Kiitz. Bacill. V. 24.
Fresh water. Aberdeenshire, Dr. Dickie. Ben M' Dhui, Mr. P. Grant.
Plate II. 17.
5. Eunotia triodon, Ehr. V. with three dorsal ridges ; striæ
40 in -001". Length -0015" to -0026". v.s.
Ehr. Inf. xxi. 24. Prit. Anim. iii. 164. Hass. Alg. xcvii. 7. Kütz. Bacill.
V. 25.
Freshwater. Ben M'Dhui, at an elevation of 3000 feet, Mr. P. Grant.
(Lapland.)
Plate II. 18.
6. Eunotia tetraodon, Ehr. V. with four dorsal ridges; striæ
24 in -001". Length -0015" to -0022". v.v.
Ehr, Inf. xxi. 25. Ralfs, Ann. vol. xiii. pi. xiv. 4. Hass. Alg. xcvii. 8.
Kütz. Bacill. V. 26.
tetraodon, Brdb. in Kütz. Sp. Alg. p. 10. ad spec, quæ misit
amie. De Brebisson, Jan. 1853.
Fresh water. Ashdown Forest, Sussex, Aug, 1850, W. Sm ^ Curwen
Hill Lancashire, Mr. G. Smith, June 1851. Quernmore, Lancashire, Aprd
1852 Mr. Johnson. Mountains in Aberdeenshire, Dr. Dic/ne. Dolgelly,
Mr. Balfs. Dolgelly Earth. Peterhead Deposit. (Manchester, Mass., communicated
by Prof. Williamson.)
Piateli. 19.
7. Eunotia Diadema, Ehr. V. with six dorsal ridges ; striæ 30 in
•001". Length-OOl6" t o -0024". v.s.
Ehr. Inf. xxi. 27. Kütz. Bacill. v. 28.
Fresh water. Dolgelly Earth.
Plate II. 20.
G e n u s 3 . CYMBEIiLA, Ag.
Frustules free, cymbiform ; valves striated, with a suhmedian line and
central and terminal nodules.
Many frustules of Cocconemata detached from their stipes bear so
close a resemblance to those of the Cymbelloe, that a discrimination
can hardly be relied upon which depends solely upon the observation
of prepared specimens. In a living state, the presence of a stipes at
once removes such frustules from the present genus. Cymbella frequently
forms a more or less distinct stratum, the frustules being retained
in their position, even when exposed to a rapid current, by the
presence of a delicate pellicle of mucus.
I. Cymbella Ehrenbergii, Kütz. V. elliptical-lanceolate, extremities
slightly produced, obtuse; striæ distinct, 15 in -OOl".
Length -0028" to '0054". v.s.
Kütz. Bacill. vi. 11. N a v i c u l a inoequalis, Ehr. Inf. xiii. 18. Frit. Anim. in.
154.
Fresh water. Living, in Lough Mourne, Sept. 1849. Peterhead Deposit.
Lough Mourne Deposit. Premnay Peat. Marl, Co. Down. (X ear Manchester,
Mass., communicated by Prof. Williamson. Very abundant in tossil eaith,
San Fiore, Italy.)
Plate II. 21. .