2^6 



DIATOMS IN HOTHAM CARRS, NEAR NORTH CAVE. 



K. H. PHILIP. 

 Hull. 



Ox the occasion of the recent excursion of the Hull Scientific 

 Club to Newport I took a gathering of Diatoms from a ditch in 

 the low-lying- country between the Chalk Wolds and the Market 

 Weighton canal, described on the map as Hotham Carrs. 

 On examination under the microscope it was found to consist 

 chiefly of a beautiful form of SnrircUa, figured and described in 

 Peragallo's ' Diatom.ees Marines de France' as Snrirella medulica 

 Per. It appears to be a variety of S. constricta W.Sm. 

 (S. Smitliii Ralfs), distinguished from the type form by its 

 straight sides. Perag-allo records this variety as found bv him 



in brackish water at Medoc, a place in the South of France 

 well known to claret drinkers. Van Heurck states that Snrirella 

 Sinithii is recorded for brackish waters in England by Wm. 

 Smith, Combes, and Stolt, and in Ireland by O'Meara. No 

 previous freshwater records appear to be known, yet here we 

 find it abundantly in a ditch at least five miles from the Humber, 

 and in country that has not been overflowed by the tide for at 

 least a centur}^, and probably for much longer. It is interesting 

 to note the survival of a brackish-water form under such con- 

 ditions. A small percentag'e of the frustules show a curious 

 distortion caused by an indentation on one side of the valve, 

 as shown in the lower figure. Peragallo's plates show similarly 

 distorted forms of Snrirella labelled as distinct species, S. 

 reiiiformis Grun. being a distortion of S. gemma Ehr. , and 

 ■S. Nentneyeri ]i\n. of S. fas/nosa Ehr. 



Naturalist, 



