54 THOUGHTS ON ANIMALCULES. 



The pharynx, or narrow part of the upper portion 

 of the alimentary canal, is surrounded by four hemi- 

 spherical muscular masses, placed opposite to one an- 

 other like the limbs of a cross, and which are very 

 obvious when in motion. Two of these masses are 

 armed with jaws and teeth, which, being formed of a 

 hard substance, can be easily disengaged from the soft 

 parts by crushing the animalcule between two plates of 

 glass. These organs exist under several types, which 

 are so constant and regular, that Ehrenberg states 

 the Rotifera might almost be arranged, like quadru- 

 peds, according to their teeth. 



Some have a long tooth in each jaw, (as in the No- 

 tommata, lign. 4), capable of being protruded, and thus 



LiGN. 4. — The Jaws and Teeth of the Notommata, highly magnified. 



a pair of powerful nippers is formed, by which the 



