Pritchard, A. (1861). A history of infusoria, living and fossil: arranged according to Die infusionsthierchen of C.G. Ehrenberg; containing colored engravings, illustrative of all the genera, and descriptions of all the species in that work, with several new ones; to which is appended an account of those recently discovered in the chalk formations. xii. Edition IV, revised and enlarged by J.T. Arlidge, W. Archer, J. Ralfs, W.C. Williamson and the author. London, Whittaker and Co., 1861., xiii + 968 pp., 40 pls.
