Phylum: Charophyta   Family: Desmidiaceae

Xanthidium cristatum Brébisson ex Ralfs

The British distribution is biased towards the north-west where it is found in the plankton of lochs but also upland pools

References: 
Coesel, P.F.M. & Meesters, K.J. (2013) European Flora of the Desmid Genera Staurastrum and Staurodesmus
John, D.M. & Williamson, D.B. (2009) A Practical Guide to the Desmids of the West of Ireland>br/> West, W. & West, G.S. (1912) A Monograph of the British Desmidiaceae, Volume 4