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2T2 NAVIGULA.
N. Scandinavica (Lag.) Ad. Schm. (sub Stauroneis in Salltv.
Bohuslan, p. 47 ; Ad. Schm. Nordsee, pi. 1, f. 29*), plate 27, fig. 764.
Valve lanceolate, with apices produced-subrostrate.
Striae radiant, reaching
to the raphe, about 10 to 11*5 in 1 c.d.m., with strong puncta, shortened near
the central nodule, where they leave a stauroneiform space, narrow, elongate.
Length, 6-5 to 10-5 c.d.m. Breadth, 3 to 3-5 c.d.m.
Marine. Bahusie (Lag.). North Sea (Ad. Schm.).
Note. Most authors have confounded this species with N. lacustris Greg.
According to authentic specimens of Gregory in our possession, N. lacustris is
a form almost typical of N. Placentula Ehr. (Syn., pi. 8, f. 28).
N. Baileyana Grun. (in Ad. Schm. Atl., pi. 6, f. 26*; N.granu-
lata Bail, nee Breb.), plate 27, fig. 765.
Valve elliptic or elliptic oval ; striae strongly granular, about 8 in 1 c.d.m.
with approximate granules at the margin of the valve, but becoming scattered
as they approach the raphe. Raphe sometimes enlarged and accompanied
by a hyaline area, equally enlarged
on each side of the valve. Central
nodule elongated, surrounded by a stauroneiform hyaline area, more or
less elongate, narrow. Length, 5 to 8 c.d.m. Breadth, 2-5 to 3*5 c.d.m.
Marine. North Sea (Hvidingsoe, Ad. Schm. ;
Bahusie CI.).
N. fraudulenta Ad. Schm. (in Atl, pi. 70, f. 60*), plate 27,
fig. 766.
Valve regularly elliptic ; stria; not reaching to the raphe, 10 in i c.d.m.
at the middle of the valve, somewhat radiant, formed of rather strong
granules, distant, leaving a small hyaline
Length, about 3 c.d.m. Breadth, almost 2 c.d.m.
Marine. North Sea (Solsvig, Ad. Schm.).
area round the central nodule.
N. marina Ralfs. (in Pritch. inf., p. 9 o 3 ; h.v.h. Atl., pi. n,
f. 16*; Type No. 118), plate 4, fig. 184.
Valve broadly oval, with sub-acute apices. Raphe surrounded by a
narrow irregular hyaline zone, somewhat enlarged round the central nodule.
Stria; radiate, 10 or 11 in 1 c.d.m., formed of very coarse puncta. Length,
6 to 7 c.d.m. Breadth, 2-5 to 3-5 c.d.m.
Marine? (Brackish water, according to Donkin). Very rare : Washings
England, Ireland, France.
of mussels (Debv).