NON-PROTOZOAN FAUNA OF SOIL 351 



2. Consuming soil bacteria and fungi. 



3. Consuming soil protozoa. 



4. Destroying other nematodes (predatory forms). 



5. Distributing bacteria and fungi throughout the soil. 



6. Taking an active part in the transformation of the soil organic matter. 



7. Improving soil aeration. 



ROTATORIA 24 



Rotatoria or Rotifera, commonly known as wheel animalcules, are 

 minute, chiefly microscopic, animals. They are mostly characterized 

 by the presence of a ciliated area, or corona, at or near the anterior end 

 of the body, which serves both for locomotion and for bringing food to 

 the mouth. Cilia are lacking on other parts of the body; in exceptional 

 cases, they may be present at the posterior end. The corona may, in 

 a few cases, be lacking. The body is usually somewhat elongated, 

 with the corona at the anterior end and a tail-like appendage at the 

 posterior end beyond the cloacal opening. The sexes are separate, 

 the male being a minute, degenerate form, without an alimentary canal. 



They are commonly found in swamps and marshes, as well as in moss 

 and forest leaves. France found the following species in the soil: 



Rotifer tarligradus Callidina papillosa 



Rotifer vulgaris Callidina ehrenbergii 



Philodina erythrophthalma Callidina mullispinosa 



Philodina aculeata Habrotrocha angusticollis 



Philodina vorax Diaschiza semiaperta 



Adineta vaga Chaelonotus macrotrichus 



A number of other forms may occur, but they have not yet been made 

 the subject of special study. 



ANNELIDA 



The annelids are represented in the soil by the earthworms (Oligo- 

 chaeta-Terricolae), whose whole life cycle is passed in the soil, and by 

 the white worms or Enchytraeids (Oligochaeta-Limicolae), which are 

 usually abundant in moist soils, especially those rich in organic matter. 



Oligochaeta-Terricolae. 2b The earthworms are characterized by their 

 flexible segmented bodies, with four rows of bristles or setae. They 



24 Harring, H. K. Synopsis of the rotatoria. U. S. Natl. Museum, Bui. 81, 

 1913; Harring, H. K., and Myers, F. J. Rotifer fauna of Wisconsin. Trans. 

 Wiscon. Acad. Sci., 21: 415-549. 1924. 



25 Michaelsen, W. Oligochaeta. Das Tierreich. No. 10, 1900. 



