ill!Ill

impressed on the species by
SCHIZONEMA. 231
the abundant formation of coleoderm. I do
not attach any importance to the form of the fronds, and in my classification
of species I follow the same order as that employed for other ISiavicula. All
the Schizonema can, in my opinion, be reduced to a very
small number of
type forms, and I only describe those, of whose existence as species there can
be no doubt.
Costae
resolvable.
No costae,
valve
striated.
ANALYSIS OF SPECIES.
f Valve quite small, being only 1 c.d.rn. in length S. corymbosum.
-., , c f Valve large, central nodule surrounded
Valve of ._i li- 1 1:
area S. Smitiiii.
several
c.d.m. in
length.
by a considerable hyaline
Valve small, central nodule without any
hyaline area . . .8. molle.
'
Valves furnished with an obvious . pseudo-stauros
No
pseudostauros.
S. crucigerum.
( Valve with strong puncta, not forming
longitudinal lines
S. Grevillei.
] Strice
l_
fine, with divisions forming longi-
tudinal lines
S. ramosissimurn.
I. Radiosse.
N. (S.) Smithii C. Agardh. (H.V.H. Atl., pi. 15, f. 33 ; Type
No. 154), plate 5, fig. 241.
Valve lanceolate, with apices somewhat produced rostrate. Raphe sur-
rounded by a very narrow hyaline zone dilated round the central nodule into
a rounded area. Stride finely divided transversely, of unequal length round
the central nodule ; the median ones radiate, the terminal convergent, about
13 in 1 c.d.m. Length, about 6 c.d.m. Breadth, 1*3 c.d.m.
Marine. Mouth of the Scheldt (V. de Bosch). England, Scotland, Ireland, etc.
N. (S.) molle W. Sm. !
Atl., pi. 15, f. 24*), plate 27, fig. 780.
(S.B.D., i, p. 77, pi- 58, 365; H.V.H.
Valve lanceolate, with subacute apices. Striae, about 14 in 1 c.d.m., slightly
radiant, reaching to the raphe. Length, 3 to 4 c.d.m.
Marine. North Sea. England (Exmouth ; Coll. W. Sm. ).
N. (S.) corymbosum Ag. (Syst., p. uj H.V.H. Atl., pi. 15,
f, 21*), plate 27, fig. 780 bis.