BRITISH DIATOMACE/E. 65 



W. Sm. Ann. 2nd Ser. vol. ix. p. 7. pi. i. 6. Prit. Anim. xLx. G. 



Marine. Coast of Sussex, Aug. 1850 and Mar. 1852, TT. Sm. Rye> 

 Mr. Jenner. Hull, Mr. It. Harrison. 



Plate XXI. 203. Outline of F. V. PI. XXIII. 203. 



10. Pleurosigma quadratum, n. sp. V. quadrangular, acute, flex- 

 ure moderate ; colour chestnut ; striae 45 in •001". Length -0030" 

 to -0105". v.v. 



Pleurosigma angulatum, W. 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 

 Williamson, July 1852. Folkestone, Mr. Capron, Nov. 1852. 



Plate XX. 204. Outline of a young (?) specimen, 204 /3. 



11. Pleurosigma angulatum, W. Sm. V. lanceolate, angular, acute ; 

 colour pale chestnut ; striae 52 in -001". Length -0066" to -OlOO". 

 v.v. 



Pleurosigma angulatum /3, W. Sm. Ann. 2nd Ser. vol. ix. p. 7 • pi. i. 8. Prit. 

 Anim. xix. 8. Navicula angulata, Quekett on the Microscope, 184H, 

 p. 438. pi. viii. 4, 5, G, 7. 



Marine or brackish water. Poole Bay, Aug. 1848 ; Belfast Bay, Aug. 1849 ; 

 Coast of Sussex, April, May and Aug. 1852, W. Sm. Coast of Lancashire, 

 Mr. Johnson. Rye, Mr. Jenner. Hull, Mr. R. Harrison. Coast of Norfolk, 

 Mr. Brightwell. 



Plate XXI. 205. 



12. Pleui'osigma .SZstuarii, W. Sm. F. frequently direct; V. 

 broadly lanceolate ; extremities obtuse, somewhat produced, flexure 

 of median line considerable ; colour a pale purple ; striae 54 in 

 •001". Length -0028" to -0052". v.v. 



Navicula Mstuarii, De Breb. in Kiitz. Sp. Alg. p. 890. ad specim. authen. 

 quae misit el. De Brebisson, Oct. 1852. 



Marine or brackish water. Shoreham Harbour, Nov. 1852, W. Sm. 



Supp. Plate XXXI. 275. 



13. Pleurosigma obscurum, W. Sm. V. linear, slightly attenuated, 

 obtuse, median line not central ; colour pale pink ; " striae 75 in 

 •001"." (R. B.) Length -0036" to -0062". v.v. 



/3. A much smaller form : marine. 

 W. Sm. Ann. 2nd Ser. vol. ix. p. 8. pi. i. 1 1 & 12. Prit. Anim. xix. 1 1 & 12. 



F 



