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REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 31
the genus Dolichospermum of Thwaites. Ralfs, in Annals and Mag. of Nat. History, Vol. V, 2d series
(1850), p. 325, following C. A. Agardh, who first described the genus Sphærozyga (Flora, 1827), says
that in Sphærozyga the spores are first formed from the cells nearest the vesicular cells (heterocysts),
as is shown by Professor Wood’s figure, Pl. 3, Fig. 3, to be the case with the species from Camden.
Neither can we regard S. Carmichaelii, Harv., as a synonym of Cylindrospermum polysporum, Kütz., as
given by Professor Wood. Although we have examined a large number of specimens, in only one
instance have we found more than a single spore on each side of the heterocyst, which is quite different
from C. polysporum, Kütz.
NODULARIA, Mertens.
(From nodulus, a little joint.)
Filaments free, trichoma inclosed in a definite sheath, cells discoidal. Heterocysts at
regular intervals. Spores numerous, contiguous, not adjacent to the heterocysts.
The genus Spermosira of Kützing is included under the above.
N. HARVEYANA, Thuret, Class, des Nostoch. (Spermosira Harveyana, Thwaites,
Phyc. Brit., Pl. 173 c.)
Filaments curved, cells discoidal, .0015-20 x .004 mm , heterocysts .0035 mm in
diameter, spores numerous, about 4-8 together, spherical, .005-70 mm in diameter.
Charles River, Cambridge, Mass.; Europe.
Found in small quantities, mixed with Sphærozyga, in company with Rhizoclonium.
SPIRULINA, Turpin.
(From spirula, a small spiral.)
Filaments simple, without a proper sheath, oscillating, spirally twisted. Spores
unknown.
S. TENUISSIMA, Kütz., Phyc. Brit., Pl. 105, Fig. 3; Farlow, List of Marine Algæ, 1876.
Pl. I, Fig. 4. [sic; should be Pl. II, Fig. 4.]
Filaments intricately interlaced, .0035 mm in diameter, hyaline, spiral, closely
twisted, cell divisions scarcely visible, oscillations rapid.
Eastport, Maine; Gloucester, Cambridge, Wood’s Holl, Mass.; Europe.
This species is common at Eastport, where it forms, mixed with species of Oscillaria, dark purplecolored
patches on the wharves at low-water mark, and it is without doubt to be found in similar
localities along the whole coast.
We found at Wood’s Holl, in 1876, a species of Spirulina which formed a greenish film on decaying algæ
five or six feet below low-water mark, and the same species was collected by Mr. F. W. Hooper at Key
West. It agrees closely with S. Thuretii, Crn, a species which differs from S. tenuissima, Kütz., in
having slightly smaller filaments, which are also less tightly coiled. It hardly seems to us, however, as
though the difference .was sufficient to separate, the two species. A Spirulina with much finer
filaments than in S. tenuissima, and with a much more open spiral, occurs at Wood’s Holl, but we have
never found it in sufficient quantity to ascertain the species.