22. Campylodiscus bicostatus, W. Sm. Valve suborbicular ; canaliculi
from twenty to thirty, interrupted, not reaciiing centre of
valve. Diameter -0015" to •0022". v.s.
W. Sm. in Roper, Mic. Trans, vol. 2. pl. vi. 4.
Marine. Thames mud, Mr. Roper. Breydon, Norfolk, July 1853, Mr.
Bridgman. Northfleet, Sept. 1854, Mr. ~
23. Campylodiscus Clypeus, Æ/«-. Valve suborbicular; canaliculi
from 40 to 100, irregularly interrupted, reaching over two-thirds of
the radius ; ridges of canaliculi, and two bands in centre of valve,
punctate. Diameter ^0042" to •0098". v.v.
Ehr. in Kiitz. Bacill. pl. ii. 5 ; in Prit. Anim. xii. 516. Microg. x. B. &c.
Brackish water. Breydon, Norfolk, Sept. 1854, Mr. Wigham. Swansea
Dock, at the depth of 25 feet, Oct. 1854, Mr. Okeden.
The last two species are closely allied, but an inspection of specimens of
both will satisfy any one of their distinctness.
The occurrence of Campylodiscus Clypeus in a living state is an interesting
fact, as hitherto it has only occurred in deposits.
24. Surirella apiculata, n. sp. Valve elliptical, ovate; smaller extremity
produced into a linear, truncate apiculum; canaliculi 15 in
•001". Length of frustule •0008" to •0012". v.v.
Freshwater. Haverfordwest, April 1854, Jfr. Okeden. Newhaven, Sussex,
Nov. 1854, W. Sm.
A close ally, if not a variety of S.
25. Surirella Amphioxys, n. sp. F. V. linear; V. elliptical-lanceolate,
extremities subaoute; canaliculi 9 in •OOl". Length of
frustule •0012". Breadth of v a lv e -0005". v.v.
Fresh water. Haverfordwest, August 1855, Mr. Okeden.
26. Surirella Crumena, Bréb. V. suborbicular ; striæ obscure ;
canaliculi 15 in -OOl". Length of frustule -0009". Breadth of
valve -0008". v.v.
Bréb. in Kütz. Sp. Alg. p. 38.
Fresh water. River Avon, Lanarkshire, July 1854, Dr. Gregory. Near
Tantallon Castle, August 1854, Dr. Gre
s. Brightwellii (Synop. pl. ix. 69), which M. De Brébisson was at first
disposed to regard as identical with this species, is distinguished from it by its
coarser and more prominent costæ and distinct striæ. The outline of both
species is nearly alike ; S. Crumena is, liowever, a smaller and more orbicular
form.
27. Tryblionella leyidensis, n. sp. V. linear, subaoute at the
extremities ; canaliculi very distinct, parallel, extending to the
central line, 5 in-OOI". Length of fru stu le -0012" to'0017". v.v.
Brackish water. Cork City Park, April 1855, W. Sm.
28. Tryblionella constricta, Greg. V. fiddle-shaped, apiculate ;
canaliculi obsolete ; striæ delicate, 40 in -OOl". Length of frustule
•0008" to-OOll". v.v.
Greg. Mic. Journ. vol. 3. pl. iv. 13. T. Soleiformis,^. Sm. MSS.
Marine. Stomach of Pecten, Coast of Sussex, Feb. 1853, and Kinsale Bay,
April 1855; Poole Bay, Sept. 1849 ; Cork Harbour, Aug. 1855, W.Sm.
Glenshira Sand, Dr. Gregory; communicated by Dr. Arnott, March 1855.
(Near Marseilles in the Mediterranean, May 1854, W. Sm. Ceylon, Dr. Kelaart.)
The surface of the valve in this species is striated as in Pleurosigma angu-
latum : the form is precisely that of Cymatopleura apiculata.
29. Nitzschia Palea, W. Sm. F. V. linear ; valve linear-lanceolate
with acute extremities. Length of frustule •0008" to •0016". v.v.
Synedra Palea, Kiitz. Bacill. iii. 27, iv. 2. Synedra Fusidium, Kiitz. Bacill.
XXX. 33. ad specimina authentica quæ misit cl. De Brébisson.
Freshwater: not unfrequent. Lewes, April 1853, &c., W.Sm. Haverfordwest,
Oct. 1855, Mr. Okeden. (Avignon, May 1854, W.Sm. Falaise,
M. De Brébisson.)
My specimens from Avignon, named S. Palea by M. De Brébisson, correspond
with authentic specimens of S. Fusidium from Falaise, sent by the same
kind friend.
30. Nitzschia lin ea r is, W. Sm.
Var./3. Valve elliptical-lanceolate. Length of frustule'0018" to -0031". v.s.
Freshwater. Derbyshire, Aug. 1853, Dr.Redfern.
A common variety ; probably the earlier condition of the frustule.
31. Nitzschia curvula, TF.Sm. F. V. linear, tapering towards the