ill!Ill

232
SCH1Z0NEMA.
Valve excessively small, elliptic lanceolate, with apices obtuse rounded.
Striae radiant, almost straight, reaching to the raphe, 20 or 21 in 1 c.d.m.
Length, 1 c.d.m. Breadth, about 0-25 c.d.m.
Marine. Coasts of Northern Europe.
II. Stauroneidese.
N. (S.) crucigerum W.Sm. !
(S.B.D., ii., p. 74, pi. 56, f. 354,
and pi. 57, f. 356; H.V.H. Atl., pi. 16, f. 1*; Type No. 151), plate 5,
fig. 242.
Valve lanceolate acute ;
central nodule prolonged up to the margins of the
valve into a stauros, which is covered with two striae more robust than the
others. Striae reaching almost to the raphe, 24 in 1 c.d.m., almost parallel,
finely divided transversely, with divisionj simulating delicate longitudinal
striae. Length, about 7 to 8 c.d.m. Breadth, about 1 c.d.m.
Marine. Scheldt at Antwerp. Blankenberghe. England, Scotland, Ireland.
The photograph has not reproduced the stauros as it is found in the
original figure. In the figure in my Synopsis the valve appears
stauros.
III. Perstriatae.
without a
N. (S.) Grevillei Agardh. (Consp., p. 19; H.V.H. Atl., pi. 16,
f. 2*; Type No. 152), plate 5, fig. 243.
Valves rather broadly lanceolate, with obtuse apices ;
striae reaching almost
to the raphe, strongly punctate transversely, the 3 or 4 median ones straight,
very distant, the others approximate, about 20 in 1 c.d.m., gently radiate up to
the apex of the valve. Girdle face quadrangular, with rounded apices, com-
pressed at the median portion ;
connective membrane with numerous longitu-
dinal striae. Length, 3 to 7 c.d.m. Breadth, about 1*5 c d.m.
Marine. Ostend (Weslendorp, n. 896 and 897), Blankenberghe. England, France, Denmark,
Heligoland.
Later researches, after the publication of the Atlas to my Synopsis, has
proved that the JS'avicula J)elognei (pi. n, f. 13) ought
form of S. Grevillei.
to be considered as a
N. (S.) ramosissimum C. Agardh. (Consp., p. 22; H.V.H.
Atl., pi. 15, f. 4*; Type No. 153), plate 5, fig. 244.