ANIMAL KINGDOM. 217 



naturalists are indebted to Lamarck, consist of animals 

 which are so far advanced in organization as to possess a 

 distinct mouth ; this mouth having, at its entrance, either 

 one or more wheel-like organs fringed and rotatory, or 

 having such organs converted gradually into tentacula 

 disposed in a circle. The Infusoria rotifera of Cuvier are 

 the Polypes possessing the abovementioned wheel-like 

 organs, which are suspected by this naturalist as well as 

 by Dutrochet to be employed for purposes of respiration. 

 It would seem indeed that some of those animals described 

 as Rotifera by MM. Dutrochet and Leclerc, are far too 

 complicated in their organization to belong to the Infuso- 

 ria ; animals which not only are in possession of an in- 

 testine, but also, having two apertures to this organ, ap- 

 proach nearer, as M . Savigny remarks, to the group we 

 shall hereafter have to describe under the name of Tuni- 

 cata. On leaving the Monades we are prepared for the 

 curious wheel-like processes of the real Rotifera, first, 

 by the genus Trichoda of Miiller, and then by the Polypes 

 vibratiles of Lamarck. The latter family, which is com- 

 posed of the genera Ratulus, Trichocerca and P < ■ ginicola, 

 has a vibratory fringe encircling the mouth, which is an 

 imperfect sketch of that of the Rotifera. 



The Infusoria rotifera are remarkable, inasmuch as in 

 them we have the first instance of a testaceous covering 

 for the animal, and consequently are led in some measure- 

 to expect the more calcareous excretions of the Polypes 

 apolypier of Cuvier, or the Polypi vaginati of Lamarck. 

 The Rotifera also present us in the genus f orticella Bl. 

 with the first example of composite animals, which we 

 shall henceforward find so common among the dcrita. 

 The Vorticella indeed are not covered with a shell, but 



