Phylum: Dinoflagellata   Family: Ceratiaceae

Ceratium hirundinella (O.F. Müller) F. Dujardin 1841

First described by Müller (1773: 63) as Bursaria hirundinella. It was later moved to its current genus and illustrated by Dujardin (1841: 377, pl. 4: 2). Widespread but not particularly common. Fairly adaptable to nutrient levels in deeper-water lochs.

References: 
Dujardin, F. (1841) Histoire naturelle des Zoophytes, Infusoires, comprenant la physiologie et la clasification de ces animaux et la manière de les étudier à l'aide du microscope.
John, D.M., Whitton, B.A. & Brook, A.J. (2011 second edition) The Freshwater Algal Flora of the British Isles.
Müller, O.F. (1773) Vermium terrestrium et fluviatilium, seu animalium infusoriorum, helminthicorum et testaceorum, non marinorum, succincta historia.