THE PROTOZOA 



around the body of the organism. A second type consists of a basal 

 tripod, the arms of which inclose the central capsule (Fig. 43). A 

 third modification is the simple alteration of the spherical latticed shell 



Fig. 42. Lichnaspis giltochh Haeck., one of the Acanthana (Actipylea). [HAECKEL.] 

 The spines are arranged in accord with the Miillerian Law as follows : a, a, a, a, northern polar 

 spines ; 6, b, b, b, northern tropical spines ; c, c, c, , equatorial spines ; d, d, d, d, southern tropi- 

 cal spines ; and e, e, e, , southern polar spines. 



into elliptical, ovate, or sub-spherical forms. Again, the skeleton 

 may be discoid, or even bivalved, and, in still other types, there may 

 be a combination of two or more of the above modifications. 



