SYSTEMATIC SURVEY, I1t 
Modified flagellate torms are included in the groups Dinoflagellata 
and Cystoflagellata, in both of which there are two flagella, differ- 
ently placed in the two cases. In the first are included Pertdindum and 
Ceratium ; in the latter, the large phosphorescent Moctdluca. They 
form an important part of the plankton of lakes and sea. 
As (9) Ciliata are included a very large number of forms, more or 
less closely resembling Paramecium or Vorticella, and very abundant 
in infusions ; some, such as Ofaina, in the intestine of the frog, are 
parasitic, 
As specially modified Ciliata are included (10) Acinetaria, highly 
specialised forms, ciliated when young, but usually furnished when adult 
Fic. 52.—Optical section of a Radiolarian (Acténomma). 
—After Haeckel. 
a, Nucleus; 4, wall of central capsule; c, siliceous shell within 
nucleus ; cl, middle shell within central capsule ; ¢?, outer shell 
in extra-capsular substance. Four radial spicules hold the 
three spherical shells together. 
with suctorial tentacles, They are fixed in adult life, and feed on other 
Protozoa. As examples may be given Acéneta ; Dendrosoma, forming. 
branched colonies; and Oshryodendron, without suctorial tentacles. 
Some, like Spherophrya, are minute and parasitic. 
D. Predominantly encysted Protozoa,—Sporozoa.—Forms. 
like Gregarina and Monocystds are included in a group of the (11) 
Sporozoa, the Gregarinida in the strict sense. They are parasites in 
the gut or body cavity of many Invertebrates, especially Arthropods. 
Cocctdium is a type of the Coccidiidea, which are intracellular parasites. 
occurring in Arthropods, Molluscs, and Vertebrates. A very im- 
portant group, with a life cycle essentially similar to that of the 
Coccidiidea, are the Hzemosporidia, which are parasitic in the red 
blood corpuscles of Vertebrates. The malaria parasites belong to this 
