f I
2. Cyclotella operculata, Kütz. V. depressed in centre; striæ
obscure, very short, 36 in OOl". Diam. '0005" to '0012". v.v.
Ag. Consp. p. 11. Kütz. Bacill. i. 1.
Frcsh water. Plumpton. Sussex, Mar. 1852, W. Sm. Lough Neagh,
Dr. Dickie. Cantyre Peat, &c.
Plate V. 48.
3. Cyclotella antiqua, n. sp. V. convex; striæ broad, not reaching
the margin. Diam. "0009" to '0013". v.s.
Fresh water. Lough Mourne and Peterhead Deposits. Cantyre Peat, and
Marl, Co. Down.
Plate V. 49.
4. Cyclotella Rotula, Kütz. V. plane ; striæ numerous, distinct,
14 in -001". Diam. -0015" to -0022". v.s.
Kiitz. Bacill. ii. 4. Discoplea atmospherica, Ehr. in Prit. Anim. xxiv. 1 & 2 ?
Fresh water. Lough Neagh, Dr. Dickie.
Plate AL 50.
G e n u s 1 2 . CAMPYLODISCUS, Ehr.
Frustules îree, saddle-shaped ; valves equidistant; canaliculi radiated.
The species included under this genus may all be recognised by
the characteristic bend or contortion of their surfaces. The costæ,
as in Epithemia, appear to arise from the presence of minute canals
which form means of communication between the internal cell-membrane
and the surrounding fluid. In one species, C. cribrosus, these
appearances are absent ; hut the presence of foramina on the margin
in this species seems to indicate the existence of canaliculi, though
these are not apparent as distinct costæ.
1 . Campylodiscus Horologium, Will. V. circular; canaliculi
about 5 0 , in length one-third of the radius; centre of V. smooth.
Diam. -0 0 5 1 " to -OOeS". v.s.
Prof. AVilliamson in Ann. Nat. Hist. May 1848.
Marine. Coast of Skye, dredged in 60 fathoms water by Mr. G. Barlee,
communicated by Pro/. ”
Plate VI. 51.
2. Campylodiscus costatus, W. Sm. Y. circular ; canaliculi from
30 to 40, in length about half of the radius ; centre of V. minutely
punctate. Diam. '0025" to -0050". v.v.
Var. ¡3. V. somewhat elliptical, disc distinctly punctate.
AV. Sm. Ann. 2nd Ser. vol. vii. pi. i. 1. Bright. Inf. pi. ix. 10.
Fresh water. Biver Frome near Dorchester, May 1849. Near Lewes,
Aug. 1850, W. Sm. Bramley Spring near Guilffiord, Mr. ’
W . Brightwell. Lough Mourne Deposit. Peterhead Deposit. Dolgelly
Earth, &c. &c. Var. f Cantyre Peat.
Plate VI. 52. Var. /3. PI. VII. 52.
3 . Campylodiscus Hodgsonii, n. sp. V. nearly circular ; canaliculi
very numerous, 100 or upwards, in length about one-third of the
radius; centre of the disc cellular; cells circular, in radiating lines.
Diam. -0018" to -0052". v.s.
Marine. Near Ipswich, Mr. Hodgson, July 1851. Poole Bay, Oct. 1851,
TF. Sm.
This beautiful species varies much in size, but presents throughout its characteristic
features. The disc is frequently traversed by “ J;
responding withits longest diameter : aF. V. shows us that this Ime is formed
by a ridge and two contiguous furrows passing across the valve It is worthy
oLemark that the ridges on the two valves of the same frustule are not
uniformly opposite, but cross each other at various angles : a similar cncnm-
stance may sometimes be noted in Eupodiscv.s and other disciform frustules.
Plate VI. 63.
4 Campylodiscus spiralis, W. Sm. F. twisted so as to present a
spiral outline; V . elliptical; canaliculi aboutSO, nearlyparallel; centre
of the disc minutely punctate. Longest diam. ‘0042" to -0083". v.v.
W. Sm. Ann. 2nd Ser. vol. vii. pi. i. 2. Surirella spiralis, Kütz. Bacill. lu. 64?
Fresh water. Bramley near Guildford, Oct. 1848, Mr. Capron L»ishaw
S p Î Î a r Katefield, Lancashire, Jan. 1852, Mr. Geo. Smith. Norfolk, Mr.
Brightwell.
Plate VII. 54. Frustule with endochrome. Frontispiece, fig. LIV.
5 C a m p y l o d i s c u s cribrosus, IL. Sir. V . nearly circular ; disc cellular
; cells irregularly circular, in radiating lines. Diam. -0041 to
•0052". v.v.