7 Prot, 
PROTOZOA. 
Section V. — Polycystina, 
Subsection 1 — Cyrtida. Subdivisions — (i.) Monocyrtida ; (ii.) 
Zygocyrtida\ (iii.) Dicyrtida\ (iv.) Sticho- 
cyrtida ; (v.) Polycyrtida. 
2 — Ethmosphcerida, 
3 — Acanthodesmida. 
Section VI. — Collozoa. Simple or compound ; if single, with skele- 
ton as circumferential detached spicula only. 
No nuclear vesicle. 
Subsection 1 — Polycollida. (Compound Kadiolarians.) Sub- 
divisions — (i.) Sjphcerozoida ; (ii.) Collo- 
sphoerida. 
Section YSl—Vesiculata. With a nuclear vesicle. 
Subsection 1 — Collida. 
2 — Sphceroidea. 
3 — A ulosphccrida. 
4 — Brachiata. 
Polycystina classified and defined by Walltch, (12), p. 375 : — 
Division I. — Cyclodina. Omphalostype symmetrical, omphalic 
chamber spherical. 
1 — Sphosrodina. Type, Haliomma. 
2 — Dichodina. Type, Amphidiscua. 
II. — Monodina. Neither omphalostype nor omphalic chamber 
symmetrical, the latter generally somewhat pyramidal. 
1 — Actinodina. Type, Aatromma. 
2 — Monodina. Type, Podocyrtis. 
' Challengeri[i~\dat Thomson (11), ii. p. 341, figs. 68 & 69. New order, 
approaching Radiolaria^ based on Challengeria^ g. n., and other forms. 
Heliozoa are equivalent to and independent of Radiolaria ; Brandt 
(Halle : 1877), cited from JB. Anat. Phys. vii. ii. p. 12. 
Genera, Species, &c., referred to. 
ActinospTicerium eichhorni. Structure and development described by 
K. Brandt, 1. c. supra. The contractile vacuoles open to the exterior ; 
nuclei saccular ; union of several individuals takes place only under 
artificial conditions ; the true pseudopodia are replaced by amoeboid pro- 
cesses just before ency station ; then the alveoli disappear, the nuclei 
decrease in numbers, increase in size ; the body breaks up into generally 
3-9 pieces ; these divide into halves, again uniting and becoming encysted ; 
before leaving the cyst the nuclei multiply ; it is infested by two para- 
sitic Flagellata. 
Actinosphcenum eichhorni (9), p. 446. Must be divided into four 
species. One of these is distinguished by a single siliceous shell, etc., 
another by a double shell; two other species show disappearance of 
the nuclei and fresh formation during fission, and have a thinner shell, 
but one alone shows a fusion of two fission-products. 
Rhaphidiophrys pallida^ described by E. R. Lankester in J. Micr. 
Soc. i. p. 393, from Britain for the first time. 
