212 FRESH-WAT£R ALG^ FROM BURMA.
The spines of this variety are looger than those present ou Turner's Indian specimens, but tho
forma observed from Ceylon, which were typical as regards general outline, likewise possessed longer
spines than the Indian forms (»iiif PI, xv, fig. 8).
122. Arthrodesmub fusifoumis sp. n. (PI. xv, fig. 4}.
A. magnus, pfene l|-plo latius quam longus (sine spinis), profundissime constrictus,
siDu aperto acutangulo; semicellalfe elliptico-fusiformes, ventre plerumque
couTOxiori qmm dorso, angulis lateralibus snbacutis spinani sublongam rectam vel
curvatum ferentibus, spinis subhorizontaliter dispositis vel leviter divergentibus; a
vertice visas fusiforme^, polis acutis spinalis. Menibrana glabra.
Long. 44-46-5/I.; lat. sine spin. 57'5-OO/I, cum spin. 78-90/X; lat. isthm. 9-5^;
crass. 20-21^.
¿Tai.—Mansang, near Hsipaw (iso. 24193).
Including the spines this species is about twice as broad as long. The cell-wall is rather thin,
and aa far as could be judged is quite smooth. It stands very near to A. /ej]todermus Liitkem.,
but is considerably larger, with longer spines, and a more fusiform vertical view, The under side
of the semieells is also more ccuves than the upper side, and the spines are slightly divergent.
123. Abthrodesmus leptodermos Liitkem. Desm. Central China, 1900, p. 120,
t. 6, f. 17-19.
minus attenuatis,
Forma semicelluUs a fronte et a vertice visis ad polof
spin. 46-50;^; lat. istbm.
ad extremuui leviter angustiori.
Long. SS'o^i.; lat. sine spin. 38'5-42^,
8-9-5/.; crass. 20,^, (Pi. xv, tigs. 5, 6).
Ifab.—Mansang, near Hsipaw (No. 24193).
The Arthrodemus figured by Wolle in his 'Desmids U. S.' lt-84, pi. 23, fig, 22, 23, as a
variety of A. convirgens with short aculei, is perhaps the nearest in general form to tho Burmese
plant, but the spines ace a Httle longer, A. vunor Tma. (Freshw. Alg. E. ludia, 1893, p. 234,
t. 11, f. 29) is possibly a small and rather more inflated form of the same plant.
5 A. hiatus Turn. (1. c. p, 134, t. 11, f, 34, 40; t. 82-f. 1),
s dorsal part of the semieells and the incurved spines.
Another closely allied i
which only diSers in the mo
124. Arthiwdesmus mdcrondlatus Nordst. Desm. Brasil. 1870, p. 232, t.
f. 58.
Forma minor, apidbus semicellularum paullo
Long. 16;i; lat. sine spin. 21/t, cum spin. ; lat. isthra. 6^.
Sai.—Mansang, near Hsipaw (No. 24193).
Genus: Staurastrum Meyen.
125. Staurastrum apiculattjm Br^b. Liste Desm. 1856, p. 142, t. 1, f. 23.
Long, cum apic. ; lat. 19-5^; lat. isthm. 7/4.
^fli.—Mansang, near Hsipaw (No. 24193).
STAURASTRUM. 213
126. Staurastrum mocronatum Ralfs in Ann. Mag. Nat. Hist. 1845, p. 152,
t. 10, f. 5, 6; W. & G. S. West, Alg. N. Ireland, 1902, p. 44,
t. 2, f. 31.
Var. subtriangulare W. & G. S. Weet, Scott. Freshw. Plankton, i, 1903,
p. 54.5, t. 17, f. 11.
Long. lat. sine spin. 29-36-5, cum spin. 34-5-41,.; lat. isthm.
6-10/:. (PI. XV, fig. 20).
^ai.—Mansang, near Hsipaw (No. 24193). In the Kan-gyi at Mudon
(No. 24505),
127. Staurastrum leptoderuum Lund. Desm. Suec. 1871, p. 58, t. 3, f. 26.
Var. iKAPoiE (Schmidle) nob.
St. Jkapow Schuiidle, Alg. aus Nyassa-See, 1903, p- 74, t. 2, f. II.
The Desmid described by Schmidle under the name of St. Ikapo<B is only a variety of St.
leptodermm Lund, with the angles less produced, and with tie spines distinctly larger and more
upwardly directed. The cell-wall is also punctate.
Forma cellulis paullo angnstioribus, spinis interdum paullo minoribus.
Long, sine spin. 40-42^, cum spin. 50-54/^; lat. 31-33/.; lat. isthm. 14-5-16/.
(PI. xvi, fig. 8).
a-flJ.—Mansang, near Hsipaw (No. 24193).
128. Staurastrum unguifsrum Turn. Freehw. Alg. E. India, 1893, p. 130,
t. 15, t 18.
Var. inerue (Turn.) nob.
St. inerme Turn. 1. c. p. 131, t. 17, f. 8.
Long. 52^^; lat. max. 36—28/^; lat. istbm. 17,^. (PL
^ffli.—Mansang, near Hsipaw (No. 24193).
S( inerme Turn, can only be differentiated from St. unguiferum by the absence of the short
terminal spines, and is therefore best regarded as var. ¿««rm. of that species.
The specimens observed from Burma are not exactly liie the deseripticn and figure given by
Turner of his Indian forms. The sides of the semiceUs are stxaighter, and towards the base are
very faintly retuse. The upwardly directed angles are somewhat tbickened and sHghtly incurved
over the apex of the semieells as in St. nnguiferum forma Turn.
St unguiferum var imrmB is very closely allied to St. corniculatwn Lund., but is proportionately
narrowed, with the angles mere produced and less spreading. It is also in^resting to note the
existence of a spinate form of St. corniculat,m~St. corniculalum var. ,pi,ugerum West-which occurs in
Europe and Australia.
129. Staurastrum unicoknb Turo. Freshw. Alg. E. India, 1893, p. 107, t. 15,
f. 16.
Var. CEYLANICUM W. & G. S. West, Freshw. Alg. Ceylon, 1902, p. 176,
t. 31, f. 16, 17.
Forma spinis rectis extrorsum divergentibus.
Long, sine spin. 30/., cum spin. 35-38^; lat. sine spio. 39-3V, cum spin. 44-49 j
l a t . isthm. 5-4m (PI. xvi, fig. 2).
g- 11).