42 BRITISH DIATOMACE^. 



/3. Synedra constricta, Kiitz. Bacill. iii. 70. ad spec, quae dedit amic. De Bre- 

 bisson. 



Brackish water. Near Lewes, Oct. 1851, W. Sm. Hull, Mr. Harrison. 

 Coast of Norfolk, Mr. ShadhoH. 



Plate XIII. 1 1 2. Plate XIV. 1 1 2. 

 Var. /3. Supp. Plate XXXI. 112/3. 



17. Nitzschia bilobata, W. Sm. F. on F. V. elliptical, with a central 

 constriction, and round or truncate extremities ; V. linear-lanceo- 

 late, acute; puncta double; keel central; striae distinct, 56 in 

 •001". Length -0033" to -OOSS". v.v. 



Amphiprora latestriata, Breb. in Kiitz. Sp. Alg. p. 93. sic cl. De Brebisson 

 in lit. Aug. 1852. 



Brackish water. Poole Bay, Oct. 1849. Shoreham, Nov, 1852. 



Plate XV. 113. 



18. Nitzschia plana, n. sp. F. on F. V. elliptical, with a central 

 constriction and acute extremities ; V. linear-lanceolate, acute ; 

 puncta in a single row; keel eccentric; surface of V. obscurely 

 striated; strise interrupted, 56 in "OOl". Length '0058" to 

 •0076". v.v. 



Brackish water. Poole Bay, June 1849, W. Sm. 

 Plate XV. 114. 



Sect. VL Valves with extremities produced. (Ceratoneis, Kiitz.) 



19. Nitzschia birostrata, TF. Sm. F. V. straiglit, in central por- 

 tion somewhat lanceolate ; extremities produced into extremely 

 long beaks ; keel nearly central ; puncta in a single row ; striae 

 obscure. Length -0128" to -0169". v.s. 



Ceratoneis longissiiiia, Kiitz. Sp. Alg. p. 891. ad specimina quae communi- 

 cavit cl. De Brebisson, Sept. 1852. 



Marine. Near Walton, Essex, Mr. Topping. 

 Plate XIV. 119. 



20. Nitzschia Closteriiim, W. Sm. F. V. arcuate ; V. faintly stri- 

 ated; striae 90 in -001" ; otherwise as in the last. v.v. 



