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7. Cosmarium o v a l e Raljs.
Plate L X X X V I . Figs. 8. and 9.
Char. Fronds large, compressed, punctated. Segments tri-
angidar, slightly truncate at the extremity. End view
broadly elliptic.
fl Segments dentated.
Cosmarium ovale Ralfs, in Annals, vol. xiv. pi. xi. fig. 7. —
fl. Euastrum No. 6. Bailey, 1. c. p. 295. fig. 28. ; J e n ner,
in loc. cit. p. 196.
Hab. Dolgelly : Mr. Ralfs. Barmouth : Rev. T. Salwey.
Near Tunbridge Wells, in a pond between Ramlyc and
Broadwater Forest ; Beckley Furnace : Mr. Jenner. —
fl. Weston bogs, near Southampton: Mr. Jenner.
The characters of the different species of Desmideæ may
generally be so accurately embodied in the definition as to
preclude the necessity of any lengthened remarks attached to
each species ; this conciseness it is to be hoped as our knowledge
of the works of creation becomes more extensive, will
be found applicable to the description of all organised productions.
8. Cosmarium Cucumis Corda.
Plate L X X X V I . Fig. 10.
Char. Y xovAz orbicular, much compressed. Segments Aewiz-
spherical, quite smooth, being neither denticulated nor dotted.
End view elliptico-lanceolate.
hleneghini, Synops. Desmid. p. 220. Euastrum integerri-
mum Ehr., Infus. p. 163. tab. 12. fig. 9. Cosmarium
Cucumis Corda, Almanac de Carlsbad, 1835, p. 206.
tab. 11. figs. 27, 28. C. Cucumis Y sMb, 1. c. p. 395. pi. xi.
fig. 8.; Jenner, in loc. cit. p. 196.
Hab. Sussex : Mr. Jenner. Dolgelly : Mr. Ralfs.
The frond is more orbicular and not punctated as in Cosmarium
ovale.
9. Cosmarium quadratum Ralfs.
Plate L X X X V I . Figs. 11. and 12.
Char. Fronds about twice as long as hroad. Segments quadrate,
in front view slightly compressed, smooth.
Ealfs, 1. c. vol. xiv. t. 11. f. 8. ; Jenner, 1. c. p. 196.
Hab. Rusthall Common, near Tunbridge W e lls : Mr.
Jenner. DolgeUy : Mr. Ralfs.
The front view of the segments is somewhat quadrangular,
the distal or free angles being slightly rounded, and the
proximate, protuberant.
10. Cosmarium Cucurbita Rreb.
Plate L X X X V I . Fig. 7.
Char. Fronds small, about twice as long as hroad, cylindrical,
with a slight constriction in the centre, minutely punctated.
End view circidar.
Ralfs, in Annals, vol. x iv .; Jenner, in Flora of Tunbridge
Wells, p. 196. Cosmarium Cucurbita Desm., No. 1103.
Hah. Dolgelly : Mr. Ralfs. Ashdown Forest and
Greatham bogs, near Pulborough : Mr. Jenner.
This species approaches rather closely to Cosmarium cylin-
drum Ealfs, but the frond in th a t species is distinctly dentated,
whereas in C. Cucurbita Breb. it is merely d o tted :
it also has a great resemblance to Closterium cylindrus, but in
th a t plant the puncta are described as arranged in longitudinal
lines, whereas in Cosmarium Cucurbita they are scattered.
59. C L O S T E R IUM Nitzsch.
Char. Fronds elongated, mostly crescentic, sometimes conjugating;
each formed o f two similar segments, which
unite without constriction, and the fre e extremity o f each