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Order 4. DicTYOTACE.i:. Olive-coloured, inartieulate seaweeds, whose spores
are superficial, disposed in dfinite spots or lines (sorij.
* Boot coated with tcoolly fibres, frond fiat.
XIV. CuTLEKiA. Frond ribless, irregularly cleft. Sori dot-bke, scattered.
Spores pedicellate, containing numerous sporules.
XV. H a l i s e r i s . Frond midribbed.
XVI. P a d in a . Frond ribless, fan-shaped, concentrically striate. Sori linear,
concentric, hm-sting through the epidermis.
XVII. ZoNAEiA. Frond ribless, lobed, concentrically striate. Sori roundish, containing
spores and jointed threads.
XVIII. T a o n ia . Frond ribless, irregularly cleft, somewhat fan-shaped. Sori
linear, concentric, superficial, alternating w ith scattered spores.
XIX. D io ty o ta . Frond ribless, linear, dichotomous. Sori roundish, scattered,
bursting through the epidermis; or, (on distinct plants) scattered spores.
* * Boot a minute naked disc. Frond cylindrical, branched.
XX. S t i lo p h o e a . Spores concealed among moniliform threads, which are collected
into convex, wart-Uke sori.
XXI. D io ty o s ip h o n . Spores irregularly scattered, solitary, or in dot-like sori,
not accompanied by moniliform threads.
XXII. S t e i a k i a . Spores in dot-like sori, ranged in transverse lines.
* * * Boot naked. Frond unbranched, cylindrical, or flat.
XXIII. PcNOTAEiA. Frond flat, leaf-like.
XXIV. A sp e e o c o o o u s. Frond membranaceous, tubular, either cylindrical or
compressed. Spores in dot-like son, mixed with a few jointed threads.
XXV. L i to s ip h o n . Frond cartilaginous, filiform, sub-solid. Spores scattered,
sub-solitary.
Order B. C h o e d a e ia c e æ . Olive-coloured seaweeds, with a gelatinous or
cartilaginous frond, composed o f vertical and. horizontal filaments interlaced
together.
* Frond cylindrical, branching.
XXVI. C h o rd a r i a . Axis cartilaginous, dense ; filaments of the circumference
unbranched.
XXVII. M e s o q lo ia . Axis gelatinous, loose ; filaments of the circumference
branching.
* * Frond either tuber-shaped, or <
XXVIII. L e a th e s i a . Frond tuber-shaped.
XXIX. E a l e s i a . Frond crustaceous.
* * * Farasites, consisting o f densely tuftedfilai
XXX. B l a c h i s t a . Filaments pencilled, rising from a tubercular base, composed
of vertical fibres.
XXXI. M y e io n em a . Tufts cushion-like ; filaments rising from a flat base, composed
of decumbent fibres.
Order 6. E c to c a e p a c eæ . Olive-coloured, articulated, filiform seaweeds,
whose spores are (generally) external, attached to the jo
* Frond rigid; each articulation composed o f numerous cells.
XXXII. C la d o s te p h u s , Bamuli whorled.
I, connected at the base, free above.
XXXIII. S p h a c e l a e ia . Bamuli distichous, mostly pinnated.
* * Frond fiaccid; each articulation formed o f a single cell.
XXXIV. E o to c a e p d s . Frond branching; ramuli scattered.
XXXV. M y e io t e ic u ia . unbranched ; ramuli whoiied, and tipped with
pellucid fibres.
• S u b - c la s s II. KHODOSPEEMEÆ OE CEEAMIALES.
(Eed* or Brown-red Seaweeds.)
Order 7. E h o d om e la o eæ . Bed or broimi-red seaweeds, with a leafy or
filiform, areolated or articulated frond, composed of polygonal cells.
Fxmt double : Concep'tacles(ceramidia) external, ovate or urn-shaped, with
a terminal pore, and containing a tuft of pear-shaped spores : 2. Tetra-
spores immersed in distorted ramuli, or contained in proper receptacles
{called here stiohidia).
X X X V I. O d o n th a l i a .
* * Brand filiform, wholly inartieulate.
X X X V II. E h o d om b la . Branches coated with minute, iiregular cells,
not involute.
X X X V III. B o s t r y c h i a . Branches dotted ; the surface cells quadrate,
strongly involute.
X X X IX . E y t ip h læ a . Branches transversely striate, at short distances.
* * * Frond filiform, partially or generally articulate.
X L . P o ly s ip h o n ia . Articulations of the ramuli two- or many-tubed. Tetra-
spores in distorted ramuli.
X L I. D a sy a . Articulations of the ramuli single-tubed. Tetraspores in lanceolate
pod-Uke receptacles (Stichidia).
Order 8. L a u e e n o ia c eæ . Bose-red or purple seaweeds, with a cylindrical
or compressed, rarely flat, linear, narrow, areolated, inarticulate, or constricted
and chambered, branching frond, composed of polygonal cells.
Bruit double-. 1. Conceptacles (ceramidia) external, ovate, with a terminal
pore, and containing a tuft o f pear-shaped spores ; 2. Tetraspores
scattered without order among the surface cells of the branches and
ramuli.
* Frond solid.
X L I I . B o n n em a is o n ia . Eose-red, excessively branched, distichous; ramuli
subulate, acute.
X L I I I . L.AUEENC1A. Purplish, yellowish, or reddish, piiinatifid or pinnate ; ramuli
obtuse.
* * Frond {at least the branches) hollow.
X L IV . C h e y sym e n ia . Frond neither constricted nor chambered.
X LV . C h y lo c l a d i a . Frond (at least the branches) constricted at intervals and
chambered.
Order 9. C o e a l l in a o e æ . Bigid, articulated, or crustaceous, mostly calcareous
seaweeds, purple when recent, fading on exposure to milk-white,
composed o f cells in which carbonate o f lime is deposited in am organized
form. Tetraspores tufted, contained in ovate or spherical conceptacles
(ceramidia) furnished with a terminal pore.
* See also Ulvaceæ and Osdllatoriacecs among the Green Algoe.
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