iimch divided, fasciculated, and fastiglate above ; frustules in numerous
closely-set files; valve elliptico-lanceolate, acute; striæ 40
in -001". Length of frond 1". Length offrustule -0015" to -0022".
Breadth of valve -0003". v.v.
Ag. Cousp. p. 18. ad specimina authentica in herb. Grev. Grev. S. C. E.
tab. 298. Grev. B. F. p. 413. Harv. Man. p. 211. ad specim. antlieu,
Kiitz. Bacill. xxvii. 5. ad specimina quæ dedit. el. De Brébisson.
Marine ; on rocks. Torbay, Mrs. Griffiths aud 3Irs. TVyatt. Swaiiage,
Dorsetshire, March 1849; Newhaven, Sussex, Oct. 18,53, &c., TF. Sm.
Burntisland Sands, and Joppa near Edinburgh, Oct. 18,53, Dr. Greville.
Sidmouth and Exmouth, Miss Cutler.
Plate LVII. 362.
7. S c h iz o n em a to r q u a tnm , TV. Sm. Frond filiform, simple below,
much divided, and fasciculated above, ultimate divisions exceed-
ingly twisted ; frustules subdistant, in numerous files ; valve lanceolate
; striæ 40 in-OOl". Length of frond 1-5". Length of frustule
-0009" to -0012". Breadth of valve -00035". v.v.
Schizonema Smithii ¡3. torquatmn, Harv. Man. p. 211. ad specimina authentica.
Marine ; on rocks, or larger Algæ. Torbav, Mrs. Griffiths. Poole Bay,
Sept 1849, TF Sm. E.xmouth, June 1854, SÎiss Cutler. Joppa near Edinburgh.
Dr. Greville.
It IS not improbable, as Dr. Harvey suggests, that the present species is a
variety of S. Smithii ; but as the contorted character of its ultimate ramuli
gives it a very characteristic appearance, and its frustules are shorter aud more
slender than those of S. Smithii, I have thought it better to figure and
describe it as distinct.
Plate LVII. 361.
8. S c h iz o n em a d iv e rg e n s , n. sp. Frond simple below, sparingly
divided, or by cohesion irregularly submembranous above; ultimate
ramuli short, obtuse ; striæ 42 in -OOl". Length of frond 1".
Length of frustule •0013" to -0018". Breadth of valve -00035". v.s.
Marine. Larne Lough, in five fathoms, Sept. 1853, Dr. Dickie.
The specimens supplied by tbe discoverer were remarkable for the diffused
arrangement of the primary divisions ; hence the name I liave adopted : the
species is closely allied to the last two.
Plate LVII. 363.
9. Schizonema Grevillii, Ay. Frond filiform, much divided from
the base; ultimate ramuli acute; larger divisions with several
files, ultimate ramuli with a single file of frustules ; valve lanceolate
; striæ 60 in 'OOl". Length of frond -5" to 1 -5". Length of
frustule -0017" to -0025". Breadth of valve -00055". v.v.
Ag. Consp. p. 19. ad specimina authentica in herb. Grev. Grev. B. F. p. 413.
Schizonema quadripunctatum et S. Grevillii, Harv. Man. p. 214. ad
specimina authentica. S. Grevillii, Kütz. Bacili, v. 1. & xxvi. 4. ad
specim. quæ dedit cl. De Brébisson. Dangia quadripunctata, Lyng.
Tent. 26 ?
Marine. Torbay, Mrs. Griffiths and Mrs. TVyatt. Pevensey Bay, Sussex,
Sept. 1850 and May 1852; Hove, Sussex, March 1851, IF. Sm. Saltcoats,
March 1854, Dr. Arnott. Frith of Forth, Dr. Greville.
The large, and on the F. V. nearly square frustules of this remarkable
species are not likely to be confounded with those of any other Schizonema,
and enable me to give the above synonymy with tolerable confidence.
Plate LVIII. 364.
10. Schizonema molle, n. sp. Frond gelatinous, simple below,
membranous by cohesion above ; margin much divided into acute
segments ; frustules in crowded files ; valves lanceolate, acute ;
striæ 48 in -001". Length of frond -6". Length of frustule -0012"
to -0015". Breadth of valve -00045". v.s.
Marine. Coast of Aberdeen, 1847, Dr. Dickie.
Cutler.
Exraouth, July 1854,
I cannot reduce this species to any of the previous, nor to any form given
in Harvey’s ‘ Manual.’ The frustules are very like those of iS. helmintosum,
but the form and structure of the frond are altogether different: in general
character, the frond belongs to the next section, being soft and flaccid, but the
frustules are firmly siliceous, and resist the action of acid.
Plate LVIII. 365.
S e c t . II. Frustules imperfectly siliceous ; striæ obscure ; frond
flaccid.
11. Schizonema Dillwynii, Ag. Frond capillary throughout,
sparingly branched, tenacious, apices acute ; frustules exceedingly
crowded towards the apices, scattered and remote in the older
portions ; valves lanceolate, acute. Length of frond 2" to 5" or