w m
our knowledge of the Algcc has been so considerably augmented.”
— Annals.
12. M E SO C A R PU S Hassall.
Char. Cells f i l e d at f r s t with endochrome, which subsequently
contracts, and assumes an irregularly spiral form.
Sporangia either circular or oval, and lodged in the transverse
tubes.
Derivation. F i’om gsaoi, middle, and Kapiros, fruit.
Sphcerocarpus Hassall, in Annals of Nat. Hist. vol. xi.
p. 185. pi. 7. fig. 7. &c.
The genus Mesocarpus, for Avhich I first proposed the name
of SphcBrocarpus, to designate Jhe position of the sporangia,
and which I now find to he preoccupied, differs from the
two genera already described in not having the endochrome
arranged in any definite and figured form. When the filaments
are young, the endochrome occupies the entire cavity
of each c e ll; as they grow older, however, spaces are left at
the extremities of the cells; and finally the endochrome
frequently contracts itself into a mere thread, irregularly
twisted. The sporangia are never placed in the cells, as in
all the species of the genus Zygnema, and in very many T yn daridece,
but invariably in the transverse tubes of communication
Avhich become dilated for their accommodation. The
species of this genus live in water, less pure than the Zygnemata
and Tyndaridea, being mostly found in boggy and
ancient ponds, on commons, &c.; and on this account they
are rarely so brightly coloured as are the species of those
genera.
1. M esocarpus scalaris Hass.
Plate X L I I . Fig. 1.
Char. Filaments exceeding somewhat in diameter those o f
Mougeotia genufexa. Cells about fo u r times as long as
broad. Sporangia oval, their long diameter being placed in
the direction o f the diameter o f the cells.
var. fl. — Sporangia circular.
Mougeotia scalaris Hassall, in Annals and Mag. of Nat
Hist. vol. X. p. 45. pi. 7. fig. 7. Zygnema ordinarium?
Berkeley’s Gleanings. Spharocarpus scalaris var.. Annals
of Nat. Hist. vol. xii. p. 186. pi. 7. fig. 8.
Hab. E ngland; common, var. fl, Crowborough Warren •
Mr. Jenner.
This IS one of the commonest as well as most distinct
species of the genus. I have encountered it repeatedly myself
and have ffso received it from Mr. Jenner. ordmarium
Berkeley is quoted as a synonyme with considerable d o u b t;
but if that species be not the one above described, I am at
a loss to which of the other species of the genus described in
this paper it ought to be referred. The filaments in Mesocarpus
scalaris, as well as in the majority of the other species
of genus, are of a yellowish green, owing to the greater
impurity of the water in which they dwelt.
Plate XLII. fig. 2. represents what I shall here describe
as a variety of this species. The filaments are of the same
diameter, but the sporangia, instead of being oval, are spherical.
I t IS very probable that this is really a distinct species; but
having seen it but once^ I hesitate so to regard it.
2. M esocarpus in tr ic a tu s Hass.
Plate X L I I I . Fig. 1.
Char. smaller than those o f M. scalaris. C e lls > e
or six times as long as broad. Sporangia oval, rather
larger than those o f M . scalaris, their long diameters being
placed in the direction o f the width o f the cells.
Spharocarpus intricatus. Annals of Nat. Hist. vol. xii
p. 186. plate 7. fig. 9.
Hab. Broadwater F o re s t: Mr. Jenner.
The only differences to be detected between this and M.
scalaris are, the smaller diameter of the filaments, and
M 4