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M ic ra ste r ia s a p icu la ta (Lhr.). Meneg. Syn. Desm. (1840), 216.
Frond orbicular, hispid all over with scattered spines; segments
5-Iobed ; basal and middle lobes once or twice incised,
tbeir external m a r /n toothed, ultimate subdivisions furnished
with two acute spines ; end lobe narrow, spinous on external
margin.
Siz e. Length 180-230 diam. 200 p (K.) ; diam. 188 p
(Kutz.); diam. 190 p (Rab.) ; length 220 /x; diam. 180 p (R.
& B.) ; length 235-260 /x ; diam. 201-227 p (T.) ; length
216 p-, diam. 194 p (D.).
Kutz. Spec. Alg. (1849), p. 170. Breb. Liste (1856), p.
120. Cleve Bidrag (1863), p. 486, Archer Pritch. Infus.
(1861), p. 727. Rabh. Alg. Eur. (1868), iii., p. 193. Lund.
Desm. Suec. (1871), p. 13. Jacobsen Desm. Denm. (1875), p.
188. Kirchn. Alg. Sohles (1878), p. 163. Raciborski Desm.
Krak. (1884), p. 22. Elfving Finska Desm. (1881), p. 6.
Roy and Bisset Journ. Bot. ^ 8 8 6 ) , p. 193, t. 269, f. 13.
Joshua Linn. Journ. (1886), p. 326, t. 22, f. 13. Wolle Bull.
Torr. Club (1886), p. 59. Delponte Desm. Ital. (1873), p. 77,
t. V, f. 1-4. Raciborski Desm. Polon. (1885), p. 40, t. v, f. 1.
Euastrum apiculatum, Ehr. Abh. der Berl. Akad. (1833), p.
245. Ehr. Infus., p. 167, t. xii, f. 2 (as E. aculeatum), Kutz.
Phyc. Germ. (1845).
Euastrum spinuUgerum, Breb. sec. Kutz.
Didymidium (Micras.) apiculatum, Reinsch. Alg. El. (1867),
p. 145.
Micrasterias fimhriata, v. ornata, Buln. Hedw. (1859), p. 21,
t. 2, f. 3.
H ab. In pools.
Westmoreland ; France, Germany, Denmark, Sweden, Finland,
Poland, Italy, India, Burma, Japan, United States.
Plate X L V I I I . , fiy . 1. a, living frond ; 5, empty frond. After W.
B. Turner.
Euastrum A rm strongiauum. Archer in Journ. L u ll. Mior. Club
IV. (1880-6), ii. 25.
This, in common with others of Mr. Archer’s species, has
been announced, but not described. He says only “ I t is an
exceedingly well-marked and distinct form. I t occurs in deep
and limpid water, the ponds being such as are kept constantly
at a maximum degree of fulness from a bottom spring.”
Siz e . Not stated.
H a b . In ponds.
Connemara.
E u a strum c r en u la tum . Bennett in Journ Boy. Micr. Soc. (1887),
p. 17, figs. 20-21.
Frond very minute. Semi-cells broadest at the apex, with
two teeth at each outer angle and one at the base ; sides concave
; apical edge with three concave crenations, of which the
centre one is the largest, sinus broad. Each semi-cell with
three prominent protuberances. Bennett Alg. Cornw. p. 17.
Siz e . Length 25 p ; diam. 11 p ; isthmus 7 p (B.).
H a b . In bog pools.
Cornwall.
Plate L X V ., fig. 3. a, living frond ; h, empty frond ; c, end view j
all magnified 600 diameters. After Bennett.
E u a strum oblongum, var. in te g rum . Bennett
Micr. Soc. (1887), p . 16, fig. 18.
Journ. Boy.
Plate L X V I ., fig . 1.
After Bennett.
a, living frond; b, empty frond ; X 400.
E u a strum crassum, var. c o rn u b ien se . Bennett in Journ. Boy.
Micr. Soc. (1887), p . 16, fig. 19.
PUte L X V ., fig. 4.
After Bennett.
living frond ; b, empty frond ; X 400.
Cosmarium 'Wrlglitianum. Archer in Journ. L u ll. Mior. Club iv.
(1880-5), p. 19.
Minute, smooth, semi-oells oblongo-elliptio, ends somewhat
retuse ; b u t this feature is so slight as to he very readily
overlooked. Zygospore tetrahedral, the angles bluntly
rounded.
S iz e . Not stated.
H ab.
Ir e la n d ; not uncommon.
Cosmarium p la ty isthm um . Archer in Journ. Lubl. Micr. Club iv.
(1880-5), p. 27.
Minute. In general outline in front, or broad view, much
resembling, say, a section of a double railway rail, th a t is to
say, th e isthmus very broad, and comparatively long, thus
th e ’ isthmus makes up a great proportion of th e whole
Cosmarium; th e semi-cells are elliptic, much broader th an
h igh the whole smooth; end view elongate-compressed,
extre’mities rounded. The lateral extremities of th e semi•'
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