Xanthidium armatum

17. XANTHIDIUM ARMATUM.

/

XANTHIDIUM.ARMATUM, (BREB.) BALFS» - Presh-water Algae of the

United States page 18, February 1872, (Smithsonian contribu»
tion to knowledge, 241)*

X» maximum, validum, solitarium Tel binatim conjuneturn, diámetro
plernmque duplo longius; semicellulis subcordatis vel angulari-
rotundatis tubérculo oentrali subelevato, truncato, margine
granulato-dentato praeditis; cytiodermate verruculoso et pro-
cessibus saepius geminatis truncatis apice inciso-furoatis in-
struoto. (R.)

SYN.-Xanthidium armatum, (Brebisson) BALFS, British Desmidiese et
BABEHHOBST, Flora Europ. Algarum, Sect, III* p. 222«

HA3.-South Carolina; Florida; Bailey, Saco Lake; (Lewis) WOOL»

Frond large, in f. v. twice as long as broad; constriction
deep, linear; segments broadest at the base; ende rounded or
somewhat truncate; spines in pairs, principally marginal,
short, stout, terminated by three or four divergent points;
central projections cylindrical truncate, the borderiidentate;
e. f. punctate. Sporangium large, orbioular, with depressed
tubercles, perhaps immature, L. 1/180". B. 1/270". (A.)

REMARK.-Fig. 17, pi. 13, is a front view of a frond, magnified 260
diameters.

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