64 BRITISH DIATOM ACE^. 



4. Pleurosigma rigidum, n. sp. V. linear-lanceolate, flexure slight, 

 extremities rounded, median line central ; colour pale straw ; striae 

 48 in -001". Length -0112" to -0152". v.s. 



Brackish water. Ipswich, Mr. T. Hodgson, Aug. 1851. 

 Plate XX. 198. 



5. Pleurosigma elongatum, W. Sm. V. lanceolate, flexure mode- 

 rate, extremities acute ; colour a clear straw ; striae 48 in •001". 

 Length -0083" to -0152". v.v. 



W. 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, JV. S7n. Hull, Mr. R. Harrison. 



Plate XX. 199. 



6. Pleurosigma intermedium, n. sp. V. lanceolate, flexure very 

 slight, extremities acute; colour pale straw; "striae 55 in -001"." 

 (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. V. linear-lanceolate, obtuse, 

 flexure hardly perceptible; colour very pale ; "striae 55 in '001"." 

 (R. B.) Length -0055" to -0066". v.v. 



Marine. Seaford, Sussex, Mar. 1852. 

 Plate XXI. 201. 



S. Pleurosigma delicatulum, W. Sm. V. lanceolate, acute, flexure 

 moderate; colour pale pink; striae 64 in -001". Length -0058" to 

 •0108". v.v. 



W. Sm. Ann. 2nd Ser. vol. ix. p. 6. pi. i. 5. Prit. Anim. xix. 5. 



Brackish water. " Brooks " near Lewes, Oct. 1850 and Sept. 1852, W. Sm. 

 Plate XXI. 202. 



9. Pleurosigma strigosum, W. Sin. V. lanceolate, obtuse, flexure 

 slight; colour pale straw; striae 44 in "001". Length "0066" to 

 •0112". v.v. 



