Natural History of the Vorticellaa. 107 



conj ligation are shown in detail, and the remarkable tuft of 

 Zoothamnium in PI. XIV. figs. 6 & 7. 



Systematic Limitation of the Family Vorticellina. 



Ehrenberg first founded the family Vorticellina nearly in 

 accordance with our present conception of it, and with 8 ge- 

 nera and 38 sj^ecies*. The systematic characters are so 

 happily seized, that the family has recently been accepted by 

 Stein essentially with the limitation given to it by Ehrenberg. 

 Ehrenberg characterized the Vorticellina " as (polygastric) 

 animalcules which possess an alimentary canal uniting the 

 stomachs, have the mouth and" efferent orifice separate but 

 placed together in the same pit, and therefore are without a 

 hinder part, which bear no carapace, and either move freely 

 individually, or are attached, and often, by imperfect self- 

 division, acquire a minute frutescent or arborescent form." 

 The eight genera united in this family were : — Sfentor, Tricho- 

 di)ia, UrocentruiHj Vorticella^ Carchesium, Ejjistylis, Opercu- 

 lariaj and Zoothamnium. Stein f, and after him Clapar^de 

 and LachmannJ, first of all, on account of the different orga- 

 nization in many respects, rightly separated from these the 

 genus of the Stentors§, now generally placed with the Bur- 

 saries, as they are ciliated over the whole body, whilst the 

 true body of the Vorticellce is naked and only bears a so-called 

 adoral circlet of cilia ; moreover the anus of the Stentors, as 

 Lachmann demonstrated, is different in position from that of 

 the Vorticellce &c. Then Clapartjde and Lachmann further 

 separated the genus Urocentrum \\ (without sufficient founda- 

 tion or investigation, indeed) from the Ehrenbergian system, 

 forming with it a peculiar family, and united Ehrenberg's 



* A very full and admirable summary of the older literature, with in- 

 dications of the earlier conceptions as to the structure and systematic 

 position of the Vorticellina, is <>-iveu by Ehrenberg in his great work, 

 ' Die Infusionsthierchen als vollkommene Organismen/ pp. 200, 209, 27/5, 

 279, 280, &c. At p. 27o especially there is a very valuable critical 

 revision of the older system of Vorficellce and of the synonyms of the 

 indi\'idual species. We learn from it tliat the genus VorticcUa alone 

 displayed no fewer than 120 specific names, which were reduced by 

 Ehrenberg to 9 for actual, distinct and well-characterized species. 



t Die Infusionsthiere auf ihre Entwicklimgsgeschichte untersucht, 

 p. 94. 



\ Etudes sur les Infusoires &c. i. p. 77. 



§ Recently, as is well known, the Stentorinne, as, indeed, was previously 

 proposed by Lachmann (Miiller's Archiv, 1850, p. 301 & p. 304, note 1), 

 have been raised by Stein (Der Organismus der Infusionsthiere, ii. p. 170) 

 to the rank of a distinct family, with the genera Stentor and Freia, and 

 placed in the order of the Infusoria Heterotricha. 



II Etudes &c. i. pp. 78 & 134. 



8* 



