Xanthidium polygonum, Hassall Pr. Alg. (1845), p. 360.
Xanthidium fasciculatum, var. polygonum, Elir. Infus.
(1838), 1 .10, f. 24, 6.
H a b . In pools, ponds, &c.
Snssex, Hants, Gloucester, Cornwall, Cliesliire, Norfolk,
Westmoreland, Lancashire, Wales, Scotland; Prance,
Germany, Sweden, Norway, Denmark, Ita ly , United States.
Plate X L V I , f i g . l . a, living frond ; h e , empty fronds; rf, end
view ; e, side view.
X a n th id iu m a n tilo p e u m . Breh. Liste Lesm. (1856),^. 134.
With the habit of X . fasciculatum, but with each segment
furnished witb four pairs of spines.
S iz e . Length, without spines, 75 g ; diam. 75 g ; zygospore
58 V (K.) ; diam. 45-50 g (Wo.).
Kutz. Sp. Alg. (1849), p. 177. Lundell Desm. Sueo.
(1871), p. 75. Nordst. Norges Desm. (1873), p. 38. Petit
Liste Desm, Paris (1877), p. 32. Kirchner Alg. Schles.
(1878), p. 155. Wolle Desm. U.S. (1884), p. 94, t. 23, f.
1, 2 .
Xanthidium fasciculatum, var. antilopeum, Eabh. Alg. Eur.
(1868), p. 223. Jacobsen Desm. Denm. (1874), p. 210.
Ealfs. Desm. (1848), p. 114, t. 20, f. 1.
Cosmarium antilopeum, Breb. in Meneg. Syn. Desm. (1840),
p. 218.
H ab. In ponds.
France, Germany, Sweden, Norway, United States.
Plate X L V I ., fig. 2. a, living frond ; I, empty fronds ; c, end view ;
d, side view,
X a n th id iu m s p in u lo s um . Bennett Journ. Boy. Micr. Soc. (1886),
p. 10, t. 2 ,f . 17.
Frond moderately large, the shape of X. fasciculatum; each
frustule elliptical, or slightly hexagonal, furnished with four
pairs of geminate curved spines about 25 g long, the whole of
the rest of the edge ciliated with closely-set spines or teeth.
Endochrome very granular, with a lighter, less granular portion
in the centre of each frustule.
Siz e . Semi-cells 80 x 40 g ; isthmus 60 g (B.).
H ab. Mountain streams.
Lake District (England).
A doubtfully distinct species.
Plate X L V I ., fig. 4. Living frond, after Bennett.
X a n th id iu m c z is ta tum . Breh. in Balfs. Lesm. (1848), p. 115, t.
19, / . 3.
Frond rather longer than broad ; constriction deep ; segments
subrenifomi, or truncate at ends, spines straight or
curved, subulate, marginal, one at each side, at the base of
the segment, solitary, the others geminate, in four pairs ;
central protuberance short, conical.
Siz e . Length 57 g ; diam. 55 g (D.) ; diam., without
spines, 50 g ; zygospore 51 g (K .) ; diam. 40-55 g (Wo.).
Archer in Prit. Inf. (1861), p. 736, t. 2, f. 18 & 23. Delponte
Desm. (1878), t. 14, f. 1-12. Cleve Sver. Desm. (1864),
p. 491. Kirchner Alg. Sohles. (1878), p. 155. Lundell
Desm. Suec. (1 8 7 1 ), p. 76. Nordstedt Norges Desm. (1873),
p. 38. Wolle Desm. U.S. (1884), p. 93, t. 21, f. 5-8. Petit
Liste Desm. Paris (1877), p. 32. Wittrock Scan. Desm.
(1869), p. 19. Wood F . Water Alg®. U.S. (1872), p. 157.
Brebisson List. Desm. (1856), p. 135. Eabh. Alg. Eur.
(1868), p. 224. Jacobsen Desm. Denm. (1 874), p. 210.
H ab. In ponds.
Sussex, Westmoreland, Cornwall, Wales, Scotland; France,
Germany, Sweden, Norway, United States.
Blate X L V I ., fig. 3. a o, living fronds; h f , empty fronds ; d, side
view ; e, end view ; g, zygospore.
var. a. z e n ifo zm e . Balfs. Lesm. (1848), p . 115.
Segments reniform, spines scarcely curved.
Xanthidium cristatum, Breb. in litt. (1846).
H ab. In ponds, &c.
Lake District, England, Sussex, Wales, Scotland.
var. 0. u n c in a tu m . Breh. in Balfs. Lesm. (1848), p . 115, t. 19, f . 3,
d e f .
Segments truncate at the ends, spines uncinate.
Lundell Desm. Suec. (1871), p. 76. Nordstedt Norges Desm.
(1873), p. 38. Brebisson Liste Desm. (1856), p. 135. Eabh.
Alg. Eur. (1868), p. 224.
H ab. In ponds, &c.
Westmoreland, Wales ; France, Sweden, Norway.
X a n th id iu m S m i th ii . Archer in Pritch. Infus. (1861), p . 736.
Frond minute, in front view about as long as broad, constriction
a wide notch, segments twice as broad as long, trapezoid ;
angles rounded, each presenting a pair of somewhat divergent,
short, minute, acute spines ; central protuberance a minute
tubercle.