THE SPOROZOA 



193 



Genus 3. Monocystis, Stein, 1848. Trophozoites characterised by 

 considerable contractility, and consequent changeability of body -form. 

 Spores navicular. Several species from Oligochaetes, one from Clymenella 

 torquata, and one from Diap- 

 tomus and Cyclops, all inhabit- 

 ing the vesiculae seminales or 

 general body-cavities of their 

 hosts. Type M. agilis, Stein 

 (Figg. 2-8). The genus Sper- 

 matophagus, Labbe, 1899 (nom. 

 nov. for Spermatobium, Eisen, 

 1895, preoccupied), for two 

 species parasitic in the vesi- 

 culae seminales of earthworms, 

 is apparently a synonym of 

 Monocystis. Genus 4. Zygocystis, 

 Stein, 1848. Adult tropho- 

 zoites generally piriform, 

 always found associated in 

 couples or threes (Fig. 36) ; 



spores biconical. Type Z. 



cometa, Stein,from the vesiculae 



seminales and general body- 



cavity of Lumbricus agricola. Two other species are known. Genus 5. 



Zygosoma, Labbe", 1899 (nom. nov. for Conorhynchus, Greeff, 1880, preoccu- 



pied). Trophozoites pear-shaped, the entire body covered with finger-like 



processes, the endoplasm filled with vacuoles ; always associated in coxiples 



FIG. 36. 



Zygocystis cmneta, Stein (par. Lumbricus cmnmunis 

 * tW individuals : b ' of 



FIG. 37. 



Pterospora maldaneorum, Rac. et Lab. (par. Liocephalus liopygus and Clymene lunibricalis). 

 a, two associated trophozoites ; the individual on the left is fully expanded, that on the right 

 is commencing to retract its processes. 6, spore showing the sporozoites coiled spirally round 

 the central mass of granular residual protoplasm, c, transverse section of a spore showing the 

 three wing-like processes and the sporozoites (four of them) in the section round the central 

 residual protoplasm. 



when full-grown. Sporulation unknown. Unique species Z. gibbosum 

 (Greeff) from the gut of Echiurus pallasii. Genus 6. Pterospora, Bacovitza 

 and Labbe, 1896. Trophozoites pear-shaped, the smaller extremity bearing 

 two groups of finger-shaped retractile processes, four in each group ; always 

 found associated in couples. Spores with dissimilar poles, the epispore 

 prolonged into three lateral wing- like expansions. Unique species P. 



13 



