I-1
6. Zygnema belle Ilass.
Char. 1 ilamcnts about a fo o t in length, with truncate extremities
; o f considerable though rather less diameter than those
o f Z. nitidum, mucous, glossy, and o f a deep and beautiful
green colour ; investing membrane o f the cells very evident,
and transparent. Cells in the young filaments scarcely so
long as broad, but their length exceeds their breadth in
those lohich have conjugated; round the interior o fth e cells
five or six loose spiral tubes may he fa in tly discerned;
these contain the reproductive globules which are large, and
distinct, loith a dark central nucleus. Sporangia oval sometimes
almost circular, and flattened, lying in inflated cells,
the cavity o f ivhich they do not fill.
Hassall, in Annals of Nat. Hist, vol.x. p. 37.
Ilab. Essex, Hertfordshire, and in several jdaces in Middlesex
; abundant: A . H. II. In the pond betAveen
Raiuslye Rocks and BroadAvater Forest, and on Ilentield
Common: Mr. Jenner.
Tliis Avell-marked species is readily distinguished from all
others by the size of its filaments, the sporangia almost circular,
and the inflated form of the cells. There is not a more
distinct or attractive species in the genus.
7. Zygnema neglectum Hass.
Plate X X I I I . Figs. 1, 2.
Char. Filaments o f less diameter than those o f Z. nitidum.
Cells rather longer than broad. Spires distinct, serrated.
Granules large. Sporangia oval, in some specimens, occasioning
a slight inflation o f the cells in which they are
lodged.
Hassall, in Annals of Nat. Hist. vol. x. p. 37.
Hab. Neighbourhood of Cheshunt and other places; common:
A .H H. Vicinity of Tunbridge Wells and in
K e n t : 3Ir. Jenner.
This species has doubtless usually been confounded Avith
Z . nitidum, of which the filaments are la rg e r; the spires
too, are generally but three in number, and the sporangia are
less acutely oval, frequently also producing an inflation of the
cells in Avhich they are lodged.
8. Zygnema cukvatum Ag.
Plate X X V I. Figs. 1, 2.
Char. Filaments nearly equal in diameter to those o f Z . neglectum.
Conjugation angular. Cells three or fo u r times as
long as broad, coalescing without the intervention o f transverse
tubes. Spires about fo u r in number, fa in tly indicated.
Sporangia oval.
Z. curvatum Ag. Conf. stritica, Eng. Bot. t. 2463. Harvey,
Hook. Br. Fl. p. 362., also in Manual. Mougeotia stritica
Kiitz. AG. D av. Siroqonium striticum Kiitz. Phyc. Generalis,
p. 278.
Hab. Ditches in Henfield Level, Sussex, and pools on
Chy-an Hal Moor, near Penzance: Mr. Borrer. Chesh
u n t: A .H .H .
This species is remarkable for the direct conjugation of the
cells, they uniting with each other AvIthout the intervention
of tubes of communication, and it is the only species of the
genus Avhich does so. By this junction of the cells Avith each
other, the filaments are bent at angles. The direct union,of
the cells and angular flection of the filaments of this species
have induced Kutzing to form a ncAV genus for its reception
under the name of Sirogonium. Z. curvatum seems in some
measure to unite the genera Zygnema and Mougeotia, that It
is nothing more than a Zygnema, hoAvever, is proved by the
endochrome being disposed in a spiral order.
9. Zygnema pellucidum Hass.
Plate X X V . Figs. 1 ,2 .
Char. Filaments o f rather less diameter than those o f Z. curvatum,
mucous, almost transparent. Conjugation))araZZe7.
Cells six or seven times as long as hroad. Spires indistinct.