1 7 6 



THE SPOROZOA 



the body (Fig. 1 9). It is purely a matter of definition whether these forms 

 be considered as Cephalina without a septum, or as Monocystida with an 

 epimerite. The Cephalina in which the body is non -septate are some- 

 times distinguished as Dicystida from those in which there is a distinct 

 protomerite and deutomerite (Tricystida). These terms are to be under- 

 stood, however, in a purely descriptive sense, and cannot be used for 



Fio. 18. 



Three specimens of Schneideria mucronata, 

 Leger (par. Bibio marci, larva), o, young 

 cephalont, attached to a host-cell, b, older 

 cephalont. c, sporont, showing traces of a 

 protomerite. (From Wasielewski, after Leger.) C 



classificatory purposes, as there is no doubt that many dicystid species 

 are derived from tricystid forms secondarily, by obliteration of the 

 protomerite (Fig. 18). On the other hand, such forms as the Doliocystidae 

 (Fig. 19) and Selenid.ium (Fig. 46) appear to be truly and primitively 

 dicystid, and are to be regarded as intermediate forms transitional from 

 Acephalina to Cephalina. 



In the aberrant forms comprising the legion Schizogregarinae, the 

 unsegmented body grows out into irregular processes, which give it an 

 amoeboid appearance, whence these forms obtained their older name, 



