DONKIN, ON DIATOMACE^. 



NavicuU nitescens, Greg. (Trans. Hoyal Soc. Edin. vol 

 XXI, part IV, pi. 1, fig. 16). 



_ Navicula formosa, Greg. (Trans. Micr. Soc. Lond vol 

 IV, pi. 5, fig. 6) . 



_ Navicula rhombica, Greg. Trans. Micr. Soc. Lond vol 

 IV, pi. 5, fig. 1). N. melius, of the same author, is obviouslv 

 a variety of this form (see Trans. Royal Soc. Edin vol xxi 

 part IV, pi. 6, fig. 101). ' 



Navicula forcipata, Grev. (Micr. Jour. vol. vii tdI 6 

 figs. 10 and 11). > i^ ■ ) 



Nitzschia virgata, Eoper. (Micr. Jour. vol. vi, nl 3 

 fig. 6). ' if ' ) 



Atthey a decora, West. (Trans. Micr. Soc. vol. viii, pi 7 

 fig. 15). This form I gathered in abundance at Cresswell so 

 long ago as June, 1857. That is long before Mr. West' or 

 Mr. Atthey were aware that Diatomacea were to be found on 

 the beach there. It is horny, and not siliceous in its struc- 

 ture, and will therefore not bear boiling in acid 



From the above list I have excluded the following forms 

 contained in the corresponding section of my former paper : 

 Navicula lahssima, Greg., a variety of N granulata • N. Max- 

 ima, Greg, identical with N. liber; N Barclay ana, Greg, a 

 large lorm ot N. palpebralis ; Amphiprora lepidoptera, Grcff 

 ^}^''}'\^^^^'^^^^^ ^^^oneoyx^Xj ■ and Cocconeis distans, Gre^' 

 ot which I have only seen an imperfect specimen. 



Section lU.Species new to Britain. 

 I. Eupodiscus tenellus, De Breb. (Fiff. 16) (^'Diatom 

 Mann, du Littoral de Cherbourg,^^ mLfires ^ la SociS 

 Imperiale des Sciences Naturelles de Cherbourg, tome ii, 



Disc colourless, slightly convex, granular; granules monili- 

 torm, arranged m convergent lines; surface of disc divided 

 into eight compartments by eight equidistant lines of coarser 

 granules reaching near to the centre ; lines on either side of 



^Zit^Z7lt ^ ^'"^ '^^^^^^^ '^^" *^^ -^^^-^ p-^^- 



Of this form De Brebisson justly remarks : 

 ..n i^.^,"'^^'*"^! ™^^8",iale de cette espece delicate est si 

 pen distmcte et se confond tellement avec les granules, qu'il 

 tTe n^or'lf'l^'"*'^ qu^eUeappartint acegen^re, silakruc- 

 Jaienf ? f^''^''''\ ^\^ disposition de ses granules n'obH- 

 geaient a ry rapporter.^^ 



Section IV.— iVm Species. 

 1. Pleurosigmafalcatum, n. sp. (PI. I, fig. l)._rorm of frus- 



