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S ta tira s triim incus, Meneg. Sjai. Desm. (1840), p. 228;
Ralfs. Ann. Nat. Hist. (1845) xv., p. 168, t. 12, f. 2 ; Jabobsen
Desm. Denm. (1874), p. 204.
E u a s trum re tusum, Kutz. Pby. Germ. (1845), p. 136.
H a e . In ponds and ditches.
Hants, Snssex, Essex, Gloucester, Westmoreland, Cornwall,
Wales, Scotland; Prance, Germany, Sweden, Norway, Denmark,
Italy, United States.
Flate X L V I I ., fig. 4. a c e fi, living fronds; b d g, empty fronds ;
hf end view ; i, zygospore.
var. a. d iv e r g en s . Archer Britch. Infus. (1S61), p.
Segments somewhat semi-orbicular, connected by a distinct
neck, sj)ines diverging.
Ealfs. Desm. (1848), p. 118, t. 20, f. 4 (exclus./. and g.).
H ab. In ponds, &c.
var. 0. con v e r g en s . Archer Pritch. Infus. (1861), p. 737, t. 3 ,f . 36.
Segments gibbous near the base ; spines parallel or converging
.E
alfs. Desm. (1848), p. 118, t. 20, f. 4, t. g. Nordstedt
Norges Desm. (1873), p. 25.
H ab. In ponds.
A r th iode sm u s c o n v e zg en s. Ehr. In f. (1838), p. 152, t. 1 0 ,/. 18.
Frond smooth, broader than long ; constriction deep, acute ;
segments elliptic, each having its lateral spines curved towards
those of the other ; ends convex. Zygospore orbicular,
smooth.
Size. Length 93 p ; diam. 58 p (D.) ; diam. 38-40 p (Wo.) ;
length, 38-42 p ; diam. 40-46 p. Zygospore 44 p (K.).
Hassall Fr. Alg. (1845), p. 357. Ralfs. Desm. (1848), p.
118, t. 20, f. 3. Archer in Prit. Inf. (1861), p. 737. Cleve
Sver. Desm. (1864), p. 489. Petit Liste Desm. Paris (1877),
p. 32. Wittrock Scan. Desm. (1869), p. 15. Brebisson Liste
Desm. (1856), p. 185. Rabh. Alg. Eur. (1868), p. 227.
Wille Nov. Sem. (1879), p. 49. Lnndell Desm. Suec. (1871),
p. 54. Kirchn. Alg. Schles. (1878), p. 156. Nordstedt
Norges Desm. (1873), p. 25. Wood F. Water Algse U.S.
(1872), p. 159. Wolle Desm. U.S. (1884), p. 95, t. 23, f.
19-21.
Xanthidium convergens, Delponte Desm. (1878), t. 14, f.
13-23.
Staurastrum convergens, Meneg. Syn. Desm. (1840), p. 228.
Ralfs. Ann. Nat. Hist. (1845), xv., p. 158, t. 12, f. 1. Jacobsen
Desm. Denm. (1874), p. 202.
Euastrum convergens, Kutz. Phy. Germ. (1845), p. 136.
Nag. Ein. Alg. (1849), t. 7 c., f. 1.
H a b . In ponds.
Sussex, Kent, Herts, Gloucester, Cheshire, Westmoreland,
Lancashire, Yorkshire, Cornwall, Wales, Scotland, Ireland ;
Prance, Germany, Sweden, Norway, Denmark, Nova Zembla,
Italy, United States.
Plate X L V I I ., fig. 1. a, c, living fronds; I, empty frond; end
view ; e, zygospore.
A z th z o d e sm u s b if id u s . B rel. Liste Lesm. (1856), fi. 135.
Frond smooth, very minute, about as broad as long;
segments somewhat arcuate, inner margin convex, outer concave,
extremities divergent, emarginate, each angle terminating in an
acute tooth ; end view compressed, fusiform, with a short acute
spine or tooth at each end.
S iz e . 18 p. with spines, 13 x 12 without spines (L.).
Archer in P rit. Inf. (1861), p. 736. Archer Micr. Journ.
(1870), pp. 90. Lundell Desm. Suec. (1871), p. 55. Rabh.
Alg. Eur. (1868), p. 226.
H a b . In pools.
Ireland ; Prance, Sweden.
Plate X L V I I I . , fig. 2. a c, living fronds; h d, empty fronds; e,
end views.
Ii
A z th z o d e sm u s t e n u i s s im u s . Archer Micr. Journ. (1864), IV., p.
175, t. 6, figs. 50-55.
Frond extremely minute, segments sub-hexagonal, opposite
lateral extremities acutely cuspidate, each upper angle furnished
on each front with a minute acute mucro, of which four in the
fusiform end view stand out divergently.
S iz e . Length 8 | p.; diam. 11 p. (A.).
Lundell Desm. Suec. (1871), p. 55. Rabh. Alg. Eur. (1868),
p. 226.
H a b . Coating the moss in Sphagnum pools.
Ire la n d ; Sweden.
Plate X L V I I ., fig. 3. a, living fro n d ; 6, empty frond; d, end
view ; c, empty frond further magnified ; e, side view ; / , end view.
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