298 



THE SPOROZOA 



points of resemblance to the Sarcosporidia, and that its position is at 



present uncertain. 



From certain freshwater Oligochaetes peculiar parasites have been 



described by Stole [112], who regards these organisms as constituting a 



distinct group of animals, named by him 

 Actinomyxidia, supposed to be inter- 

 mediate in position between Myxo- 

 sporidia and Mesozoa. Stoic's memoir 

 is in Bohemian, but an abstract is given 

 by Mrazek (Zool. Centralbl., vii., 1900, 

 p. 594), who considers these parasites to 

 be Myxosporidia allied to Ceratomyxa. 

 Stole distinguishes three genera, Hex- 

 actinomyxon, Triactinomyxon, and Synac- 

 tinomyxon (see Fig. 115 and description). 

 Phylogeny. Thelohan, whose investi- 

 gations upon the Myxosporidia form the 

 bulk of modern scientific knowledge of 

 the group, considered the disporous 

 forms as being at once the highest and 

 the most primitive members of the 



C. 



Fio. 115. 



Figures of " Actinomyxidia," after Stolfi [112]. a, Hexactinmnyxon psmnmoryctis, Stolfi (par. 

 Psammoryctes barbatus). b, Synactinomyxon tnbificis, Stole (par. Tubifex rivulorum). c, Triactino- 

 myxon ignotum, Stole (par. CUtellio sp.). d, upper portion of Hexactinomyxon showing two of 

 the three polar capsules, one with filament discharged. 



entire order. The Disporea all live freely as amoeboid organisms in 

 the bile or urine ; they exhibit the greatest capacity for locomotion 

 by means of their highly specialised pseudopodia, and their repro- 

 duction is perhaps of a primitive type in that each trophozoite pro- 

 duces but a single pansporoblast. The genus Sphaerospora connects 

 them with the Polysporea, which on this view are to be considered as 



