Bursaridium Lauterborn, 1844 (ref. ID; 7706) or 1894 (ref. ID; 2013)
Class Kinetofragminophora: Subclass Vestibulifera: Order Bursariomorphida (ref. ID; 2013)
Class Polyhymenophora: Order Heterotrichida (ref. ID; 7303)
Suborder Bursariomorphina Fernandez-Galiano, 1978: Family Bursariidae Dujardin, 1840 (ref. ID; 7706)

[ref. ID; 2013]
Body approximately ovoid in shape with the anterior markedly truncate and the posterior broadly rounded. The ventral surface is divided by a wise slot which leads into the deeply invaginated peristomial cavity which opens apically. The cytopharynx is bent towards the animal's right which distinguishes this genus from Bursaria and Thylakidium in which genera the cytopharynx bends towards the animal's left. There is a line of membranelles which winds clockwise around the opening of the peristomial cavity on the anterior edge of the body and dips down into the cavity on the left. The body is uniformly ciliated. The macronucleus is elongate and there is a single terminal contractile vacuole.
Quote; Colin R. Curds "British and other freshwater ciliated protozoa Part I Ciliophora: Kinetofragminophora" Cambridge University Press, 1982 (ref. ID; 2013)

Bursaridium difficile Kahl, 1927 (ref. ID; 1621, 4609) reported year? (ref. ID; 1618) reported author and year? (ref. ID; 7303)
See; Bursaridium pseudobursaria (ref. ID; 4609, 4613)
Description; Anterior end truncate, cytopharynx slanting toward right. (ref. ID; 1618)
A large (120 x 70 um) and barrel-shaped freshwater ciliate. The surface area of a barrel-shaped body with the dimensions of B. difficile, 120 x 70 um, is 3.4 x 10E-4 cm2. (ref. ID; 7303)
Occurrence and ecology; The animals live in lakes and are active during the winter, forming cysts in the summer season. (ref. ID; 7303)
Measurements; About 130 um long. (ref. ID; 1618)
Bursaridium pseudobursaria Faure-Fremiet, 1924 (ref. ID; 1219, 1335, 1621, 1629) or (Faure-Fremiet, 1924) Kahl, 1927 (ref. ID; 2856, 4488, 4609, 4613)
Syn; Bursaridium difficile Kahl, 1927 (ref. ID; 4609, 4613); Thylakidium pseudobursaria Faure-Fremiet, 1924 (ref. ID; 4609, 4613)
Description; Our investigations show that its location (close above the circumoral ribbon formed by the anterior end of the somatic kineties) and structure (single row of dikinetids) are very similar to that of Paracondylostoma. The sole difference is that the paroral dikinetids, which have only one basal body ciliated, are more loosely spaced laterally and dorsally than ventrally. (ref. ID; 2856)