359 



a good many forms remain for a future communication. He added, 

 that even now, after he had explored 600 slides of it, new forms 

 were still occasionally found. 



He then gave a list of about thirty additional known species, 

 which had been noticed since the former paper was read, many of 

 them having been last year described by himself as now fresh- water 

 species, and others not having been yet described, but to be described 

 and figured in vol. ii. of Smith's Synopsis. These are : — 



Navicula Westii. 

 ,, Hennedii. 

 „ Pandura, Brib. 

 „ rostrata. 

 Pinnularia megaloptera. 

 „ biceps. 



„ linearis. 



„ subcapitata. 



„ gracillima. 



Pleurosigma distortum. 



„ intermedium. 



Gomphonema subtile. 

 Diatoraella Balfouriana. 

 Orthosira spinosa. 

 ,, mirabilis. 



Amphora menibranacea. 

 „ hyalina. 

 „ salina. 



Cymbella sinuata. 



Ampbiprora paludosa. 



Campylodiscus Ralfsii. 



Actinocyclus radiatus, 



Actinocyclus (sp. ?) This is a species 

 to be figured in Vol. IT. of the Sy- 

 nopsis, but I do not know how it is 

 named. 



Actinoptychus duodenarius (new to 

 Britain ?) 



Nitzschia bilobata. 



Eupodiscus tenellus, Brib. (new to 

 Britain ?) 



He stated that he had actually found and sketched the last two 

 forms in this deposit three years ago, but had not been able to study 

 them fully, till after they had been found and named, the former by 

 Drs Greville and Balfour, and Professor Smith, the latter by Mr 

 Okeden. He had also found both these forms in soils from South 

 America, and gave his reasons for suspecting 0. mirabilis to be an 

 abnormal state of 0. spinosa. 



He then proceeded to describe the following new species, of which 

 very exact drawings by Dr Greville were exhibited :— 



1. Navicula rhombica, n. sp. 



2. E'avicula maxima, n. sp. 



Both of these had been figured in the former paper, but were 

 now better understood. N. rhombica occurs in packs, like packs of 

 cards. 



3. Kavicula formosa, n. sp. 



9. Ifavicula Hennedii, Sm., of which 

 the deposit yields very fine speci- 

 mens. 



10. Navicula angulosa, n. sp. 



11. „ Pandura, Brib. ? 



12. „ nitida, Sm. ? 



13. „ splendida, n. sp. 



14. „ incurvata, n. sp. 



