3'
:
380 desmidea:.
zu Berlin, 1833 (1832), p. 2 4 7 .; Ehr. Infus. p. 162.
pi. xii. fig. 5.; Ralfs, in Annals, vol. xiv. pi. vi. fig. 3.;
Jenner, in Fl. Tunb. Wells, p. 1 9 8 .; Pritch. Infus.
p. 196. fig. 125. Cosmarium verrucosum Menegh.,
Synops. Desmid. in Linnasa, 1840, p. 222.
Hah. Cheshunt: A . H. H. Rusthall Common, and Ashdown
Forest: Mr. Jenner. Penzance: Mr. Ralfs.
This is a very distinct species and the only British one of
the genus which has a dentated frond.
2. E uastrum oblongum Ralfs.
Plate XCI. Fig. 1.
Char. Frond laiye, smooth, ohlong, oval, dotted, three or fo u r
times longer than hroad. Segments in front view five-
lobed, semi-oval; lobes hroad, suhcuneate, emarginate : in
lateral view pyramidal, furnished with six tubercles each.
Euastrum pecten, Abhandl. der Akademie d. Wissensch. zu
Berlin, 1831, p. 82. Euastrum pectenYMc., Infus. p .l6 2 .
pi. xii. fig. 4 . ; Pritch. Infus. p. 196. Echinella oblonga
Grev., in Hook. Br. Fl. vol. ii. p. 398. (1830). Cosmarium
oblongum Menegh., 1. c. p. 221. Eutomia oblonga
Harv., Man. Br. Al. p. 1 8 8 .; Ralfs, in Annals, vol. xiv.
p. 189. pi. V . fig. 4 . ; Jenner, in Fl. Tunbridge Wells,
p. 198.
Hab. Bogs at Fisher’s Castle; Rusthall Common; Warbleton,
&c., Beckley : Mr. Jenner. Penzance, Dolgelly,
and Caernarvon : Mr. Ralfs. Aberdeen : Dr. Dichie.
High Beech: A. H .H .
This is the finest species of the genus, and a beautiful
microscopic object, as are most of the species of this genus.
3. E uastrum P elta Ralfs.
Plate XCI. Fig. 3.
Char. Frond three times as long as broad, subquadrilateral.
euastrum. 381
compressed, dotted. Segments in front view three-lobed;
lateral lobes each twice slightly emarginate ; in lateral view
much compressed.
Cosmarium Pelta Corda, Almanac de Carlsbad, p. 121. C.
Pelta Menegh., Synops. Desmid. p. 222. Euastrum
Pelta Ralfs, in Annals, vol. xiv. pi. vii. f. 1 . ; Jenner,
loc. cit. p. 198.
Hah. Bogs at Fisher’s Castle and on Ashdown Forest;
Piltdown Common : Mr. Jenner. Dolgelly ; Penzance:
Mr. Ralfs. High Beech; A. H. H.
There is no other species with which this need be contrasted.
4. E uastrum D idelta Ralfs.
Plate XC. Fig. 8., and Plate XCI. Fig. 11.
Char. Frond about three times as long as broad, dotted.
Segments in front view pyramidal, and laterally usually
twice emarginate ; in transverse somewhat four-lobed, and
in end view oval.
Heterocarpella, Didelta Turp.,Mem. p. 295. (1828). Heterocarpella
polymorphaYvXz., Synops. Diatom, in Linnsea,
1833, p. 70. fig. 82. Euastrum ansatum, Abhandl. d.
Akademie Wissensch. zu Berlin, 1831, p. 82 .; Ehr.
Infus. p. 162. t. 12. fig. 6. Cosmarium lagenarium, Almanac
de Carlsbad, 1835, p. 206. pi. ii. fig. 26. Cosmarium
Didelta Menegh., 1. c. p. 219. Euastrum Didelta
Ralfs, in Annals, vol. xiv. pi. vii. fig. 2.; Jenner, in Flora
of Tunbridge Wells, p. 198,
Hab. Frequent in Sussex: Mr. Jenner. Henfield: Mr.
Rorrer. Cheshunt: A . H. H. Barmouth Road : Rev.
T. Salwey. Caernarvon ; Dolgelly, near Carmarthen ;
and Penzance: Mr. Ralfs. Aberdeen: Dr. Dickie.
A very distinct species.