218 ON THE CLASSES OF THE 



have a contractile body, rather dilated, and fixed by a pe- 

 duncle to different solid substances, so as singularly to re- 

 present certain monopetalous flowers. Of this nature is 

 Vorticella convallaria. But the resemblance of such 

 animals to flowers becomes still more manifest in the com- 

 posite Vorticella, or those whose peduncles ramify ; the dis- 

 covery of a species of which {Vorticella digitalis) on a 

 Monoculus quadricornis made De Geer, though a man 

 to whom the wonders of nature were daily familiar, break 

 out into raptures of admiration at the endless variety of 

 the works of his Creator. 



A celebrated naturalist pretends to trace animal nature 

 from its most complicated organization to its simplest form ; 

 but nothing, among innumerable instances to be found in his 

 work of his having forgotten this principle, can better show 

 how widely apart anatomical skill is from skill in classifi- 

 cation, than his placing the genus Hydra, " les animaux de 

 cetie classe reduits a leur plus grande simplicity " at the 

 head of his Polypes. There seems however to be great 

 reason for supposing, with Lamarck, that these simply 

 constructed Polypes and the Rotifera are connected to- 

 gether by means of the Vorticella. 



Leaving the Rotifera, we arrive at the Polypi vaginati, 

 by means of the genus Tubicolaria Lam., which possesses 

 the tubular oblong form and ciliated retractile mouth of 

 the Plumatella Lam. In true Polypes the rotatory organs 

 with which the mouths of the Infusoria rotifera are armed 

 become tentacula, or feelers. These however are no longer 

 mechanical instruments for creating whirlpools in the wa- 

 ter, but sometimes simple, sometimes dentated, or ciliated, 

 appear always to be furnished with muscles sufficiently 

 strong to enable them to secure their prey and to conduct 



