244 Prof. H. Fol on the Family Tintinnodea. 



new species, all of which they refer to the genus Tinttnnus, 

 at the same time remarking that the structure of the tests 

 would allow the establishment of a series of generic divisions. 

 In fact among the species which they describe there are some 

 which have a gelatinous test, others an agglutinant test, others 

 a test with small cavities on the surface, and, lastly, others 

 with a delicate smooth test. 



On the other hand Ehrenberg (VI.) separated from the 

 Tintinni properly so called another genus, including three 

 species and characterized by a test perforated like a trellis or 

 grate. This genus received the name of Dictyocysta, Ehr. 

 • So far all went well. The structure and history of the 

 Tintinnodea were imperfectly known, it is true ; but at least 

 there were included under this name only forms the relation- 

 ship of which was real and the characters of which were 

 ascertained in their principal features. Then came Stein 

 (VIII.) , who, by an incredible confusion, introduced disorder 

 into the whole characteristic of the group. In fact this natu- 

 ralist found in the fresh waters an Infusorian with a very 

 elongate test, sometimes free, sometimes fixed ; this Infuso- 

 rian has only a single spiral row of cilia on the peristome, a 

 row which terminates in the pharynx. The surface sur- 

 rounded by the peristome is smooth, and can be elevated and 

 depressed like the piston of a pump. What does our author 

 conclude from this ? That this Infusorian belongs to some 

 genus allied to the Vorticellce but essentially different from 

 the Tintinni'i By no means ! Stein concludes that he has 

 before him the true type of the genus Tintinnus^ the relation- 

 ship of which he establishes in consequence, throwing doubt 

 upon at least a part of the results of Clapar^de and Lachmann. 

 Not being acquainted with the Tintinnus fiuviatilis^ I cannot 

 pass any judgment upon the accuracy of Stein's description ; 

 I must accept it such as it is ; and then it is evident to me 

 that the German author has seen an animal very different 

 from that which serves as type for the family, an animal 

 which has no interest for us here, since it lies outside the 

 scope of the present memoir. The conclusions which Stein 

 draws from it, as to the characters of the genus Tintinmis^ lead 

 to error. 



I specify still further. The authors who preceded Clapar^de 

 and Lachmann made no observations upon the arrangement 

 of the cilia suiTounding the peristome. Clapar^de and Lach- 

 mann recognize that Tintinnus inquilinusj the type of the 

 genus, bears several rows of cilia around a hollow peristome j 

 and they give this character not only to the genus Tintinnus^ 

 but also to the family Tintinnodea. Our genus is and must 



