Difflugia varians Penard, 1902
Diagnosis: shell usually yellowish to brown, covered with small mineral grains and diatom fragments, embedded in an organic cement. Shape elongated ovoid, very irregular, somewhat compressed, fundus usually with one to three, sometimes four conical horns with broad base, but these horns are not always present; nucleus vesicular with one central nucleolus.
Dimensions: Penard gives as mean 100-125 µm. My measurements 94-160 µm.
Remarks: A very remarkable and extremely variable species which is rather rare. I have found it on three locations in the Netherlands, but Hoogenraad & De Groot (1940) have never recorded this species.