CHAP. XI. SENSES OF MOLLUSCA. 41 



obviously impossible, however, to determine the extent 

 of their sensations. Among these, the Vorticella Con- 

 vallaria is one of the most elegant species of this class ; 

 the body of which, formed like a bell-shaped flower, 

 is perfectly transparent. The Vorticella rotatoria, or 

 wheel animal, belongs to the same genus ; and it is so 

 called from the similitude of the head, in some posi- 

 tions, to a pair of toothed wheels in rapid motion. This 

 creature is gifted with such an amazing power of re- 

 vivescence, as to return to active life after being stretched 

 out, and apparently dead, for many months.* The 

 Triscoda Sol is so termed from its bearing the appear- 

 ance of a sun, being a little globe or ball covered with 

 long diverging rays. It is of a remarkably inactive 

 nature, affixing itself to the stem of some small water 

 plant, and occasionally moving at the rate of about a 

 quarter of an inch in an hour. Its size may be con- 

 sidered as gigantic for one of the animalcule tribe, 

 being equal to that of a small pin's head. 



(51.) Zoophytes are not supposed to possess any sense, 

 save that of touch, which, Cuvier remarks, in them, is so 

 extremely delicate, as to be acted upon by light alone.t 

 Polypes are certainly impelled to seek the sustenance 

 necessary for their support (in the places to which they 

 may be affixed) by the expansion of their several parts; 

 and many of them sensibly contract upon collision with 

 any other body. They have also, as is well known, the 

 singular power of reproduction, in so extraordinary a 

 degree, that, if cut into many pieces, each division, in a 

 few days, will become a perfect being. Animal flowers, 

 or sea anemonies, exhibit an evident sensibility to light, 

 a fact clearly demonstrated by various experiments 

 made by the abbe' Dicquemaire upon the Actinia 

 Anemonoides, or purple sea anemone. Hughes, in his 

 History of Barbadoes, also, tells us, that whenever his 

 fingers approached within two or three inches of the 

 Actinia Calendula, or sea marigolds, in his attempt to 



* Shaw's Zoological Lect H. p. 220. 

 t Cuv. Anat. Comp. vol. ii. p. 362. 



