322 



COOMBE I ALGiE FOUND AT ROCHE ABBEY 



Proceeding to the Lake close to the Abbey ruins, it was but a few- 

 minutes before I detected upon the surface of this picturesque water 

 a small piece (about an inch square) of that peculiar-looking yellowish- 

 brown scum which to an experienced eye is a certain indication 

 of a 'good find' of Diatomacese. Upon examination under the 

 microscope the gathering, of which, needless to say, I very quickly 

 secured a tube, proved to be in many respects similar to an extremely 

 fertile one I made some three years ago from the lake at Thoresby. 

 Its special feature was its richness in unusually large frustules, -ooi" 

 in length, of Pleurosigma attenuatiim, which, after careful cleaning 

 and boiling in nitric acid, give a brilliant opal iridescence of great 

 beauty under dark ground illumination with a magnification of two 

 or there hundred diameters. 



I have been able to identify and to mount in Canada balsam, 

 and also dry, the following 58 species of the Diatomaceae in this 

 one gathering, of which over 40 may be seen on a single slide under 

 a I in. circular cover glass : — 



Navicula tumida (W. Sm.). 

 Stauroneis anceps (W. Sm.). 

 Cymatopleura solea (W. Sm.). 

 Cymatopleura elliptica (\V. Sm.). 

 Cymatopleura apiculata (W. Sm.)- 

 Cymbella cuspidata (W. Sm.). 

 Vmphora ovalis (\V. Sm.). 

 Amphora minutissima (W. SmA 

 Diatoma vulgare (W. Sm.). 

 Diatoma elongatum (W. Sm.). 

 Odontidium harrisonii (W. Sm.). 



Odontidium mutabile (W. Sm.). 

 Odontidium parasiticum (W. Sm.). 



Denticula sinuata (?) 



Gomphonema curvatum (W. Sm.). 

 Gomphonemaconstrictum(W.Sm.) 



Cyclotella kutzingiana ( W. Sm.). 

 Cocconeis placentula (W. Sm.). 

 Synedra ulna (W. Sm.). 

 Cocconema lanceolatnm (W. Sm.). 

 Cocconema cistula (W, Sm.). 

 Cocconema cymbiforme (W. Sm. )• 

 Encyonema prostratum (W. vSm.)- 

 Encyonema csespitosum (W. Sm.). 

 Achnanthes exilis (W. Sm.). 

 Eunotia monodon (W. Sm.). 

 Melosira varians (W. Sm.). 

 Fragilaria capucina (W. Sm.). 

 Colletonema neglectum (W. Sm.)- 



Pleurosigma attenuatum (W. Sm.). 

 Pleurosigma hicustre (W. Sm.). 

 Pleurosigma spencerii (W. Sm.). 

 Nitzschia sigmoidea (W. Sm.). 

 Nitzschia parvula (W. Sm.). 

 Nitzschia amphioxys (W. Sm.). 

 Tryblionella angustata (W. Sm.). 

 Tryblionella gracilis (W. Sm.). 

 Surirella biseriata (W. Sm.) 

 Surirella ovalis (W. Sm.). 

 Surirella linearis (W. Sm.). 

 Pinnularia viridis (W. Sm. ). 

 Pinnularia viridula (W. Sm.). 

 Pinnuiaria oblonga (W. Sm. ). 

 Pinnularia gracilis (W. Sm.). 

 Pinnuiaria acuta (W. Sm.). 

 Pinnularia radiosa (W. Sm.). 

 Navicula cuspidata (W. Sm.). 

 Navicula firma (W. Sm.). 

 Navicula amphisbsena (W. Sm.). 

 Navicula elliptica (W. Sm.). 

 Navicula gtbbenda {W. Sm.). 



Navicula inflata (W. Sm.). 

 Navicula affmis (W. Sm.). 

 Navicula cryptocephala (W. Sm.). 

 Navicula binodis (?) 



Navicula bleischii (?) 

 Navicula veneta (?) 



Navicula producta (W. Sm.). 



The time of year and want of rain were not favourable for 



Desraids, but I came across a few 



vigorous specimens 



of the 



Natural 



