2 1 0 PEESH-WATER ALG^ FSOM BURMA.
basalibus late rotundatis et apice subtruncato, margine laterali unoquoque spiais minutis
5 - 7 (pleramque) prajdito, spiiiis ad ángulos basale« saspe subirregukriter dispositis et
numerosioribus ; a vertice visíe ellipticai, spinas minutis 2-3 ad polos et seriebus leviter
divergcutibus duobus spinoruui intra poluni unumqiiemquo ; a latore visee subsph^ricoB,
spinis minutis 'Z ad apicom; membrana delicatissime acrobiculata et minutissime
punctulata inter scrobiculos, cum zona scrobiculorum prominentiorum in seriebus subirregularibus
2 - 3 trans basin semicellulnrum juxta isibmum.
Long, sine spin. 51/i; cum spin. OSS/J.; lat. sine spin. 42ia, cum spin. -IG'Sm;
lat. isthm. 23/^; crass. 32^.
Hab.—Rangoon. (Joshua).
Josliua's desoriptioa oí " Cusmarium spinosum" is very iucomplete, and his figure is ioexaot.
H e figures a single row of promineut sorobiculatioas «cross the base of each semicell, but bis
specimens show a zone of these scrobioulations composed of two or three rather irregular rows.
The number of paira oí lateral spines is commonly five or six, but near the basal angles of the
semieells there ore often one or two additional ones.
There is little doubt that X'intliidium pulchrum Turn. (Preshw. Alg. E. India, 1893, p. ]02,
t . 13, f. 10) is merely a form of X. spiaosum. The seruioells are of the same shape, the
sinus and the isthmus are precisely similar, and he also figures one of the rows of larger
Ecrobiculaticns aerosa the base of the semicells. The additional spines at the basal angles ai'e
sometimes met with in the Burmese species. Turner's vertical vipw (f, 10 4) is obviously inaccurate.
We are inclined to think that X. brevicorne Turn, is also a form of X . spmosum, Turner
h a v i n g failed to find the surface markings. X. eximium Turn, should also be enquired into with a
view t o its relationship with X. spiiioium.
Forma membrana scrobiculata in parte centrali semicellalarum et membrana tota
minutissima punctata,
Long, sine spin. 48-49/í. cum spin. 50-ol/x; lat, sine spin. 39-43/i, cum
spin. 42-48-5/i ; lat. istbm. 20-ó-23/i; crass. (Pj. sv, figs. 2, S).
Uab In the Kan-gyi at Mudon (No. 34505).
118. XANTHIDIDM BDEKILLII s p . n. ( P L xv, fig. 10).
X. submediocre, tam longum quam latum (sino spinis), profunde constrictum, sinu
angusto extremo ampliato et extrorsum aperto ; semiceìlulaì irregulariter subhexagona?,
parte inferiori ventricosa, anguHs basalibus rotundatis, angulis lateralibus et apicalibus
mamillatis et spina elongata recta instructis, parte superiori laterum concavis, apice
subrecto ; a vertice visaì subellipticaì, polis bimamillatis, mamilHs binis poli uniuscujusque
cum spiois divergentibus instructis ; in centro semicellularum leviter incrassato et eerie
scrobiculorum 4 juxta et supra iatlimum ; angulis mamillatis semicellula rum subirregulariter
dispositis.
Long, sine spin. 44ÍT, cum spin. 73-77M ; lat. siae spia. 44-45^, cum spin.
77~8lp.-, lat. i s t h m . 16'5/X ; c r a s s . 24//.; l o n g , s p i n , 1 8 ' 5 - 2 0 / ^ . .
Mansang, near Hsipaiv (No. 24193)
This species possesses the same number of spines as S . nntilopeBum (Bréb.) Kutz., but they
are more irregularly disposed, rather longer, and each one is attached at the apex of a mamillate
projection.
AETHKODESMUS. 211
1 1 9 . XANTIIIDIOM SEXMAMILLATDM ep. n. (PI. xv, figs. 11, 12).
X. subaiediocre, paullo longius quam latum (sine spinis), profundissime constrictum,
sinu late aperto et obtuso ; semicellulíe transverse suboblongo-ellipticíe, parte superiori
mai'ginum lateralum trimamillato, mamilla unaquaque spina perlonga recta pr^dita
spinis iutcrioribus subhorizontaiiter dispositis, spinis superioribus et medianis sursum
divergentibus, projectione parvo infra mamillam inferiorem utrobique, apice concavo vel
nonnunquam recto; a vortice visee ellipticee, polis leviter attenuatis et spina perlonga
prfeditis, tumore minufo vel membrana incrassata ad medium utrobique. Membrana punetata,
in centro semicellularum leviter incrassata.
Long, sine spin. 40-48-5/^, cum spin. 66-5-76^ ; lat., sine spin. 34-5-40/^, cum.
spin. 67-81;.; lat. isthm. 7-5-9-5A') crass. 18-23^.
I/ai.—Mansang, near Hsipaw (No. 24193). In the Kan-gyi at Mudon (No. 24505).
This species comes nearest to X. Béngalkum Turn., but is distinguished by its TOády open
sinus and tbe form of the semioells. The sis spine.s of each semicell are situated on the apices
of six mamillate projections, which are absent from X Benyalicum. The thickened area in the centre
of the semioells is somewhat variable, and' may be represented by an internal thickening of tbe
cell-wall, or by a very small, projecting tumour.
V a r . EOBUSTDM—var. n. ( P I . xv, fig. 13).
Var. sinu minus aperto, spinis inferioribus ^ t medianis utrobique brevioribus
et validioribus, spinis superioribus minutis (multe reductis).
Long, sino spin. 45^, cum spin. 52-54M; lat. sine spin. 46/I, cum spin. 71/I
lat. isthm. ; eras?. 27/^.
líaí.—Mansaug, near Hsipavr (No. 24193).
Genus: Arthrodesmus Ehrenb.
120. ARTHRODESMÜS TRIANGULÄKIS Lagerh. Bidr. Amerik. Desm.-fl. 1885, p. 244
t. 27, f. 22.
A. Incus (Bréb.) Hass. var. iriangularis Lagerh, in Nuova Notarisia,
iv, 1893, p. 182,
Forma cellulis lon^ioribus quam forma typica, dorso semicellularum elevatiori et
minus vetuso.
Long. 20-24m; lat. sine spin. 16-19^1, cum spin. 43-16^; lat. i&thm. 4-3-5-3/i
(PI. XV, fig. 7).
/Ja¿.—Mansang, iiear Ilsipaw (No. 24193).
1 2 1 . ARTHRODESMÜS CÜRVATUS T u r n . F r e s h w . Alg. E. I n d i a , 1893, p. 135, t. 11,
f. 31, 33; t. 12, f. 2, 7, 13, 15.
V a r . BÜRMENSIS v a r . n. (PI. xv, fig. 9).
Var. cellulis diametro circiter l | - p lo longioribus, sinu plus aperto ; semicellulis
obsemicircularibus, apice valde convexo.
Long. 47^; lat. sine spin. 36-5^, cum spin. 87/^; lat. isthm. 11-5/*.
¿Tai.—Mansang, near Hsipaw (No. 24193).