248 



THE PROTOZOA 



encystment. Examples : Actinophrys (Fig. 46), Actinosphcerium 

 (Fig. 3), Camptonema (Fig. 47), etc. 



SUBORDER II. : CHLAMYDOPHORA. Body protected by a soft gela- 

 tinous envelope, but without solid skeletal elements. Example : 

 Astrodisculus. 



SUBORDER III. : CHALAROTHORACA. Body invested by a soft 

 envelope containing isolated spicules, usually siliceous, sometimes 

 chitinous. Examples : Acanthocystis (Figs. 18, 64, 68), Wagneretta 

 (Figs. 48, 102), Heierophrys (Fig. 103). 



SUBORDER IV. : DESMOTHORACA. Body invested by a continuous, 

 lattice-like skeleton. Example : Clathrulina (Fig. 19). 



^o. 103. Helerophrya fockei, Archer, c., c., Contractile vacuoles ; ., radial ohiti- 

 nous spines surrounding the envelope. A nucleus is present in the body, but 

 is not shown ; the bodies in the protoplasm represent zooxanthella?. From 

 Weldon and Hickson, after Hertwig and Lesser. 



A certain number of genera must be mentioned which are of doubtful 

 position, referred by some authorities to the Heliozoa, by others to other 

 orders. Some of these genera perhaps do not represent independent, " adult " 

 forms, but may be only developmental phases of other genera. Nudearia, 

 classed by some in the Aphrothoraca, by others in the Proteomyxa, has an 

 amoeboid body and pseudopodia without axes. As described above (p. 177 

 and Pig. 80), a Nuclearia-stage occurs in the development of Arcella. 



Especially remarkable are certain genera which indicate a close relation- 

 ship between Heliozoa and Flagellata. An account of several such forms is 

 given by P&aard (302), in addition to which the following may be noted : 

 Ciliophrys, Cienkowski, has two phases ; in the one it appears as a typical 

 Heliozoon with stiff radiating pseudopodia; in the other it is a typical 

 flagellate. In the process of transformation the Heliozoon-form retracts its 

 pseudopodia, its body becomes amoeboid, and a flagellum grows out ; finally 



