Prof. H. Fol on the Family Tintinnodea. 243 



The union is tolerably extensive and very intimate, and lasts 

 for several hours. During this time the copulated individuals 

 cannot withdraw into their tests ; they are condemned to re- 

 main in the state of extension ; and althougli their natation is 

 almost as rapid as that of the isolated individuals, this circum- 

 stance is none the less favourable to the study of the arrange- 

 ment of the vibratile cilia of the disk. I believe that without 

 these copulated individuals I should never have succeeded 

 completely in unravelling the question of the mode of implan- 

 tation of the cilia of the peristome. 



Systematic Part. — The genus Tintinnus was established, if 

 I am not mistaken, by Otto Friedrich Miiller (L). But 

 under this name that author included a whole miscellaneous 

 group of diverse forms described in a very unsatisfactory 

 manner. Schrank (II.) and afterwards Ehrenberg (III.) 

 circumscribed the genus, and took as its type (and this is im- 

 portant to note) a marine form, Tintinnus, inquilinus, Schrank, 

 to which Ehrenberg added a second (also marine) species, 

 Tintinnus suhulatus, Ehrenb. 



Dujardin (IV.), again, confounded the Tintinni with ano- 

 ther and very different genus, namely the Vaginicolce, and 

 grouped together animals some of them free, others sessile, 

 and which had no real relationship. Neither this author noi* 

 his predecessors give us descriptions which enable us to dis- 

 tinguish with certainty the animals of which they speak, or 

 especially to form any idea of their organization. It is only 

 by means of the figures they give (which, moreover, are very 

 rough) that we have been able subsequently to ascertain the 

 species named by them. 



Clapar^de and Lachmann (VII.) are the first authors who 

 have given us any precise knowledge as to the structure of 

 these Infusoria. They very justly take as the types the 

 marine species described by Ehrenberg, and group round 

 these first species a whole series of allied forms. They very 

 well describe the form of the body, and the form and structure 

 of the peduncle ; they point out with perfect justice the impor- 

 tant fact that the Tintinnodea have nothing comparable to the 

 disk of the VorticellcBy and that the vibratile cilia form several 

 rows round the peristome. Where the disk of the Vorticellce 

 is situated, there is here only " a concave depression, the 

 bottom of which goes rising towards the peristome, and 

 becomes confounded with it." Clapar^de and Lachmann 

 ascribe to all the Tintinnodea a ciliary coat covering the 

 whole body of the animal. This assertion is too general ; for 

 there are species, indubitably belonging to this group, of which 

 the body is absolutely smooth. Our authors describe fifteen 



18* 



