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4. Pleurosigma rigidum, n. sp. V. linear-lanceolate, flexure slight,
extremities rounded, median line central ; colour pale straw ; striæ
48 i n -001". L en g th -0112" t o -0152". v.s.
Brackish water. Ipswich, Mr. T. Hodgson, Aug. 1851.
Plate XX. 198.
5. Pleurosigma elongatum, W. Sm. V. lanceolate, flexure moderate,
extremities acute ; colour a clear straw ; striæ 48 in -OOl".
Length -0083" to -0152''. v.v.
AV. Sm. Ann. 2nd Ser. vol. ix. p. 6. pi. i. 4. Prit. Anim. xix. 4.
Marine and brackish water. Poole Bay, June 1849 ; Coast of Sussex,
Oct. 1850, TF. Sm. ilnW, Mr. R. Harrison.
Plate XX. 199.
6. Pleurosigma intermedium, n. sp. V. lanceolate, flexure very
slight, extremities acute; colour pale straw; “ striæ 55 in -OOl".”
(R. B.) Length -0066" to -0088". v.v.
Marine. Newhaven, Sussex, Mar. 1852, TV. Sm. Ipswich Harbour,
Mr. Topping, April 1852.
Plate XXI. 200.
7. Pleurosigma Nubecula, n. sp. Y . linear-lanceolate, obtuse,
flexure hardly perceptible; colour very pale ; “ striæ 55 in -OOl".”
(R. B.) Length '0055" to -0066". v.v.
Marine. Seaford, Sussex, Mar. 1852.
Plate XXI. 201.
8. Pleurosigma delicatulum, TV. Sm. Y . lanceolate, acute, flexure
moderate; colour pale pink; striæ 64 in -OOl". Length -0058" to
•0108". v.v.
AAA Sm. Ann. 2nd Ser. vol. ix. p. 6. pl.i. 5. Prit. Anim. xix. 5.
Brackish water. “ Brooks ” near Lewes, Oct. 1850 and Sept. 1852, TF. Sm.
Plate XXI. 202.
9. Pleurosigma strigosum, TV. Sm. Y . lanceolate, obtuse, flexure
slight; colour pale straw; striæ 44 in -OOl". Length •0066" to
•0112". v.v.
AV. Sm. Ann. 2nd Ser. vol. ix. p. 7. pl.i. C. Prit. Anim. xix. G.
Marine. Coast of Sussex, Aug. 1850 and Mar. 1852, TF. Sm.
Mr. Jenner. Hull, Mr. R. Harrison.
Plate XXI. 203. Outline of P. V. PI. XXIII. 203.
Rye<
10. Pleurosigma quadratum, n. sp. V. quadrangular, acute, flexure
moderate; colour chestnut ; striæ 45 in-OOl". L en g th -0030"
to •0105". v.v.
Pleurosigma angulatum, AV. Sm. Ann. 2nd Ser. vol. ix. p. 7. pi. i. 7 & 9.
Prit. Anim. xix. 7 & 9.
Marine or brackish water. Poole Bay, Aug. 1849; Coast of Sussex,
Aug. 1850; Braunton, Devonshire, Mr. Ralfs. Menai Straits, Professor
TFilliamson, July 1852. Folkestone, Mr. Capron, Nov. 1852.
Plate XX. 204. Outline of a young (!) specimen, 204 ß.
11. Pleurosigma angulatum, TV. Sm. Y . lanceolate, angular, acute ;
colour pale chestnut ; striæ 52 in -001". Length -0066" to -0100".
Pleurosigma angulatum ¡3, AV. Sm. Ann. 2nd Ser. vol. ix. p. 7. pi. i. 8. Prit,
Anim. xix. 8. Navicula angulata, Quekett on the Microscope, 1848,
p. 438. pi. viii. 4, 5, 6, 7.
Marine or brackish water. Poole Bay, Aug. 1848 ; Belfast Bay, Aug. 1849 ;
Coast of Sussex, April, May and Aug. 1852, TF. Sm. Coast of Lancashire,
Mr. Johnson. Bye, Mr. Jenner. HaU, 3Ir. R. Harrison. Coast of Norfolk,
Mr. Brightwell.
Plate XXL 205.
12. Pleurosigma Æstuarii, TV. Sm. F. frequently direct; AA
broadly lanceolate ; extremities obtuse, somewhat produced, flexure
of median line considerable; colour a pale purple; striæ 54 in
•001". Length -0028" to -0052". v.v.
Navicula Æstuarii, De Breb. in Kütz. Sp. Alg. p. 890. ad specim. authen.
quæ misit cl. De Brebisson, Oct. 1852.
Marine or brackish water. Shoreham Harbour, Nov. 1852, TV. Sm.
Supp. Plate XXXI. 275.
13. Pleurosigma obscurum, TV. Sm. V. linear, slightly attenuated,
obtuse, median line not central ; colour pale pink ; “ striæ 75 in
•001".” (R. B.) Length -0036" to -0062". v.v.
¡3. A much smaller form ; marine.
AV. Sm. Ami. 2nd Ser. vol. ix. p. 8. pi. i. 11 & 12. Prit. Anim. xix. 11 & 12.
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