The Scottish Naturalist. 



203 



18. Fontigenum, Nordst. 



Tilly four. 



19. GemmiferuM) Breb. 



Tonley ; Baldyoin Dam. 



20. Gradafum, n. sp. 



Medium sized, one-fifth longer than broad ; ends truncate inclining to concave ; 

 base slightly reniform ; constriction deep, segments close, lower and 

 upper angles acutely rounded, sides curved with 6-7 undulations rather 

 than granules which are larger upwards ; surface granulated in regular 

 radiating double rows from the marginal undulations half way to the 

 centre, where there is a large granulated prominence ; ends slightly wavy ; 

 side view of semi-cell globular ; end view elliptical, with large granulated 

 protuberance on each side. 



Length, 42 ; breadth, 35 ; isthmus, 12. Pond, Haughton. 



This may ultimately prove to be Cos. formosulum of Nordstedt's " Desmidieer 

 fran Bornholm," p. 194, Tab. VI., fig. 6 — 7 ; but in the meantime it is 

 preferred to record it under the M.S. name by which it has been long 

 known in this country, in which, as well as in Ireland, it is widely dis- 

 tributed. 



21. Granaium, Ralfs. 



Tonley. 



22. Impress iilum^ Elfv. 



Little Don ; Tonley. 



23. Isthmoclwndrum^ Nordst. 



Tonley. 



24. Margaritiferum (Turp.) Archer. 



Towie ; Tillyfour. 



25. Melanosporum, Archer. 



Correnie ; Little Don. 



26. Meneghini, Breb. 



Whiteley Marsh ; Pond, Haughton; &c. 



27. Ochthodes^ Nordst. 



Waterside, Haughton ; Dam, Little Don. 



28. Ornatwn, Ralfs. 



Towie ; Ditch, Meikle Moss, Alford. 



29. Phaseolus, Breb. 



Tillyfour. 



30. Polygonum, Nag. 



Whiteley Marsh. 



31. Portianum, Archer. 



Tonley ; Little Don. 



