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4. Tryblionella punctata, n. sp. V. elliptical, acuminate, striated ;
striæ moniliform, 31 in -OOl"; canaliculi obsolete. Length -0012"
to -0021". v.v.
Marine. Coast of Sussex, sparingly, Sept. 18.50, TF. Sm.
Plate X. 76. a’. Supp. Plate XXX. 261.
5. Tryblionella acuminata, n. sp. V. linear, acuminate; canaliculi
obscure ; striæ delicate, 40 in ’OOl", interrupted ; alæ obsolete.
Length -0025" to -0042". v.s.
Marine and brackish water. Poole Bay, June 1849 ; Belfast Bay, Sept.
1849; near Lewes, Dec. 1850, TF. Sm.
Plate X. 77.
6. Tryblionella angnstata, n. sp. V. as in the last species ; striæ
continuous, 36 in -001". Length -0021" to -0040". v.v.
Freshwater. Iford, Sussex, Oct. 1852, 11'. Sm. Guildford, Mr. Capro«.
Supp. Plate XXX. 262.
G e n u s 1 5 . CYMATOPLEURA, TF. Sm.
Frustule free, oblong, or elliptical ; valves undulated.
The undulations of the surface of the valves separate the present
genus from both the last ; the absence of alæ and canaliculi are further
characters which leave no room for hesitation as to its distinctness.
1 . Cymatopleura Solea, TV. Sm. F. V. oblong, linear; V. fiddleshaped,
symmetrically divided by a central sinus on each margin ;
undulations six ; surface of V. striated ; striæ 18 in '001". Length
•0042" to -0115". v.v.
W. Sm. Ann, 2nd Ser. vol. vii. pi. iii. 9. Navieula lihrilis, Ehr. Inf. xiii. 22.
Prit. Anim, xviii. 9. Surirella Solea, Kiitz. Bacill. iii. 61. Sphincto-
cystis lihrilis, Hass. Alg. cii. 3.
Freshwater: common. Lewes, May 1850, and Oct. 1852, See., TF. Sm.
Plate X. 78. Frustule with endochrome. Frontispiece, fig. LXXVTII.
2. Cymatopleura apiculata, n .sp . V. fiddle-shaped, apiculated;
undulations about four. Length -0021" to •0051". v.v.
C. Solea, W. Sm. Ann. 2nd Ser. vol. vii. pi. iii. 8.
In numerous localities with the former. I am not certain that the present
is entitled to rank as a distinct species ; it is usually much smaller than the
former and of a more rounded outline, but intermediate specimens sometimes
occur, and in Ehr. Inf. xiii. 22. fig. 2, copied in Prit. Anim. pi. iii. fig. 155,
we have a form as large as Solea with distinct apicula as in the present species.
Plate X. 79.
3. Cymatopleura parallela, n. sp. V. linear, extremities attenuate,
ohtuse. Length •0021" to •0048".
Fresh water. Iford near Lewes, Oct. 1852, TF. Sm.
Supp. Plate XXX. 263.
4. Cymatopleura elliptica, TV. Sm. V. broadly elliptical, somewhat
acuminate, with four or five undulations ; surface obscurely
striated. Length -0016" to •0055". v.v.
Surirella elliptiea, Brtfo. in Kiitz. Spec. Alg. p. 37. ad specimina qnæ communicavit
cl. De Brebisson, Aug. 1852. AV. Sm. Ann. 2nd Ser. vol. vii.
pi. iii. 10 & 11. Frit. Anim. xriii. 7-
Fresh water: frequent. Biver Frome, May 1849. Plumpton, Sussex,
April 1852. Guildford, Mr. Capron, &c. &c. ’ The larger variety in Lough
Mourne and Peterhead Deposits, Dolgelly Earth, &c.
Plate X. 80.
5. Cymatopleura Hibemica, TV. Sm. A'", orbicular, with prominent
subacute extremities ; undulations three ; striæ obscure. Length
•0022" to -0052". v.s.
AV. Sm. Ann. 2nd Ser. vol. vii. pi. iii. 12.
Fresh water. Lough Neagh, Co. Antrim, Dr. Dickie. Hiver Bann, Mr.
Cocken.
Plate X. 81.
G e n u s 16. NITZSCHIA, Hass.
Frustules free, elongated, comiircssed ; valves linear, keeled, with one
or more longitudinal lines of puncta ; keel frequently eccentric.
T'his genus embraces a large number of species, ditl'ering in form