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REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 91
cylindrical; fructification in broad bands or large irregular spots, or occasionally
covering the whole surface of frond, composed of large broadly clavate or wedgeshaped
paraphyses and oval unilocular sporangia.
Fronds cylindrical.................................................................... Chorda.
Fronds with a midrib.
Fronds perforated with holes ................................................. Agarum.
Fronds entire, with lateral leaflets at the base of laminaAlaria. Fronds destitute of
midrib.
Cryptostomata present.......................................................Saccorhiza.
Cryptostomata wanting......................................................Laminaria.
CHORDA, Stack.
(From chorda, a string.)
Fronds olive-brown, attached by a disk, simple, cylindrical, hollow, with diaphragms
at intervals; cells of tubular portion elongated, hexagonal in section, lined on the
inside with filaments, which at intervals are woven together so as to form the
diaphragms; whole surface of the frond clothed with cuneate-clavate cells
(paraphyses), which form a cortical layer; unilocular sporangia ellipsoidal, situated
between the paraphyses, growth basal; plurilocular sporangia unknown.
A small genus, consisting of three or four species, which are by some writers placed in the
Chordariaceæ and by others in the Laminariaceæ. The typical species, C. filum, may be regarded as the
lowest representative of the Laminariaceæ, inasmuch as it has the basal mode of growth and the
unicellular paraphyses of that order, but a simple frond in which there is no distinction of stipe and
lamina. See, also, remarks under Scytosiphon.
C. FILUM, Linn. (Scytosiphon filum, Ag.—Chorda filum, Phyc. Brit., Pl. 107; Annales
des Sciences, Ser. 3, Vol. XIV, Pl. 29, Figs. 5-10.) Pl. VI, Fig. 1.
Fronds gregarious, cartilaginous-lubricous, quarter of an inch in diameter, from one
to twelve feet long, attenuate at base, densely clothed with hyaline hairs;
paraphyses cuneate-clavate, slightly longer than the sporangia and overlapping
them.
On stones at low-water mark and below.
Common along the whole coast; Europe.
At once recognized by its cord-like appearance. The early form, which is densely covered with hairs,
constitutes the C. tomentosa of some writers. Areschoug, however, considers that the true C. tomentosa
of Lyngbye is distinct, and characterized by its elongated linear paraphyses, which are scarcely as long
as the sporangia, which ripen early in the season, while those of C. filum ripen in the latter part of
summer and autumn.