Pleurotaenium trabecula

« PI EUlfrOT>CNIUM TRABECULA,B2.J4i-

PLEUROTA3NIQM (TRABECULA, (EHRB.) HAEGELL. - Fresh-water Algae of the

United States page 18, February 1872* (Smithsonian contribution to

knowledge, 241).

P. saepe valde elongatum, octies viciea-longius quam latum,cylin-
draceum, utroque fine laevissime attenuatum ant inorassatum,
juxta medium constrictum saepius bigibbum (quasi biundatum),
apioibua late trunoatum; cytiodermate tenui laevi, achroo. (R)

Dia».-l/750" = .0013".

Syn.-"3)ooidlum Ehrenbergii* RALFS" BAILEY, Microscopical Observa-
tions* Smithsonian Contributions.

Pleurotaenium trabecula, (EHB) NAEGELI. RABSHHORST, Flora
Europ* Algarum, Sect* III* p* 141*

Hab*-South Carolina, Georgia, Florida; Bailey* Pennsylvania; WOOD

(Docidium Ehrenbergii* RALFS*) Frond slender, linear; auture

forming a very sharply defined rim; segments 8-12 times longer
than broad, basal inflation having another smaller one above it,
sides otherwise straight, parallel; ends orenate, owing to a
number of emarginations on the edge of the truncate extremities,
from three to five of the orenations being usually visible; e*
f. punoete or rough with minute granules. Sporangium suborbi-
cular or elliptic, or slightly angular, smooth, placed between
the deciduous empty fronds* Ciliated zoospores formed by seg-
mentation of the cell oontents, and their emission effected
through the opened apex of each one, two or three, especially
formed lateral tubes arising from beneath the base of one of the
segments* Archer*

REMARKS *-Thi s species is quite common around Philadelphia; but I

do not remember ever to have seen one with the cell-wall granu-
late* The smaller of the two umbonations near the oentre is
often wanting or exceedingly small, and the crenulations in the
ends are very often obsolete*

Fig. 9, pi* 12, represents a oell of this species magnified
160 diameters*

02014872