li:
Ili
m ■ .
I
I i
(
tion of the vesicles containing the active molecules, which in
Closterium Trabecula as in all other Closteria hitherto described
are placed near to each extremity of the frond.
13. Closterium margaritaceum Ehr.
Plate L X X X V I I I . Fig. 5.
Char. Frond cylinch'ical, narrow, two to eight times as long as
broad, somewhat quadrangular, often slightlg constricted,
striated. Striæ denticulated. Cells containing the revolving
particles distant from each extremity.
Ehr. Infus. p. 93. pi. v. fig. 13. ; Jenner, in loc. cit. p. 196.
Hah. Piltdown Common ; Warbleton ; and in the pond
between Eamslye and Broadwater F o re st: Air. Jenner.
A distinct and very interesting little species : it is some
eieht or ten times smaller o than Cl. Trabecula.
14. Closterium D igitus E hr
Plate L X X X V I I I . Fig. 4.
Char. Frond broad, ovate, cylindrical, fo u r or fiv e times
as long as broad ; transverse lines o f division sometimes
triplex. Endochrome/ascZafeJ. LandiS fiv e or six, often
waved.
Closterium digitus, Abhandl. der Akademie d. Wissensch.
zu Berlin, 1831, p. 68. Pleurosicyos Myrio{q)d)dus
Corda, Almanac de Carlsbad, 1835, p. 182. t. 5. f. 68,
69. Cl. Digitus ? Menegh., 1. c. p. 236.
Hab. Bogs at Fisher’s Castle, Ashdown Forest ; Scrubbs,
Colebrook Park, and between Heathfield and Warbleton
: Mr. Jenner. Aberdeen : Dr. Dichie.
This is one of the finest and most distinct of the numerous
species described by Ehrenherg, whose figures of Closteria
are most beautiful and accurate, and whose descriptions
are not less so. The species of this genus being for the most
377
part of considerable size do not require for their satisfactory
examination the high and delicate powers with which most of
the Desmideæ need to be examined.
60. T E TM EM O B U S feaZfr.
Chai'. Frond elongated, straight, subcylindrical, slightly constricted
in the centre. Segments emarginate at their extremities
but otherwise entire, being neither lohed nor
sinuated.
Derivation. From Tsgvo), to cut.
The two species for the reception of which this genus has
been created are placed by Meneghini in the genus Closterium
with the other species of which they do not well accord.
From Closterium it differs in the emarginate extremities of
the segments, and in the absence of the cells containing the
revolving particles : from Cosmarium it is separated by the
divided segments, as well as by its elongated fronds.
From Euastrum, with which it agrees in the terminal
division of the segments, it differs in being neither lobed nor
sinuated.
1. T etmemorus B rebissoni Ralfs.
P la te L X X X IX . Fig. 5.
Char. Frond about fiv e times as long as broad, considerably
constricted in the centre. Segments in the fro n t view
somewhat quadriform, hut in the lateral view attenuated,
longitudinally striated. Crannies in a row dawn the
centre o f the frond.
Closterium Brebissoni Menegh., Syn. Desmid. in Linna;a,
1840, p. 236. Closterium (sp. 9.) Bailey, American
Bacillaria, in Amer. Jour, of Science and Arts, vol. xii.
No. 2. pi. i. fig. 38. Tetmemorus Brebissoni Balfs,
Ann. vol. xiv. p. 258. pi. viii. fig. 1. ; Jenner, in Flora
of Tunbridge Wells, p. 198.