BRITISH DIATOMACE^. 51 



22. Navicula gibberula, K'dtz. V. inflated at the centre, linear 

 towards the rounded extremities, v.v. 



Kiitz. Bacill. iii. 50*. 



Freshwater. Lewes, Feb. 1851, 7F. S'jw. Guildford, I/?-. Ca/)ro?«. Lough 

 Mourue Deposit. Cautyre Peat. Marl, Co. Down. Dolgelly Earth. Ben 

 M-^ Dhui, Mr. P. Grant. 



Plate XVn. 160. 



Sect. V. Valves with extremities produced. 



23. Navicula amphirhynchus, Ehr. V. linear, abruptly contracted 

 towards the produced extremities ; striae faint, 48 in 'OOl". Length 

 •0020" to -0036". v.v. 



Kxitz. Bacill. xxi. 11. 



Freshwater. Lewes, Oct. 1851, W. Sm. Lough Mourne and Peterhead 

 Deposits. Premnay Peat and Dolgelly Earth. (San Fiore, Italy.) 



Plate XVL 142. 



24. Navicula producta, n. sp. V. elliptical, abruptly contracted 

 towards the produced extremities; striae faint, 42 in "OOI". v.v. 



Freshwater. Lewes, Oct. 1851, W. Sm. East Shalford, Mr. Capron. 

 Plate XVII. 144. 



25. Navicula ambigua, Ehr. V. elliptical, gradually contracted 

 towards the obtuse extremities, which are produced ; striae distinct, 

 parallel, 36 in -001". Length -0021" to -0033". v.v. 



Ehr. in Kiitz. Bacill. xxviii. QiQ. 



Freshwater. Lewes, Oct. 1851, W. Sm. 



Plate XVI. 149. Frustule with endochrome, Frontispiece, fig. CXLIX. 



26. Navicula Amphisbsena, Bory. V. elliptical, constricted towards 

 the extremities, which are rounded and produced ; striae delicate, 

 40 in -001", not reaching the central line. Length •002l"to -0032". 



/3. Extremities slightly produced, obtuse. Length -0017" to -0027". v.v. 



Kiitz. Bacill. iii. 41 and 42 /3. Ehr. Inf. xiii. 7. Prit. Anim. iii. 141. 

 Hass. Alg. cii. 5. 



E 2 



