258 



HANDBOOK OF PROTOZOOLOGY 



Skeleton composed of strontium sulphate Suborder 1 Actipylea 



Skeleton not composed of strontium sulphate 



The central capsule uniformly perforated; skeletons are either tangential 

 to the capsule or radiating without reaching the intracapsular region 



Suborder 2 Peripylea 



The central capsule not uniformly perforated 



The capsule monaxonic which bears at one pole a perforated plate form- 

 ing the base of an inward directed cone Suborder 3 Monopylea 



The capsule with three openings (one astropyle and two parapyles) .... 



Suborder 4 Tripylea 



Suborder 1 Actipylea Hertwig 



Radial spines, 10 to 200, not arranged according to Muller's law 



Legion 1 Actinelida 



Spines radiate from a common center. Haeckel considered these as the 



ancestral forms Family 1 Actineliidae 



Genus Actinelius (Fig. 103, a) 



With 10 to 16 diametral spines irregularly arranged 



Family 2 Acanthociasmidae 



h \\ /Y 



Fig. 103 a. Actinelius primordialis . X24 (After Haeckel). 



b. Acanthociasma planum. X65 (After Miehk). 



c. Acanthometron elasticum. (After Hertwig). 



d. Acanthoma tetracopa. X40 (After Schewiakoff). 



e. Amphilonche hydrometrica. X130 (After Haeckel). 



f. Hexaconus serratus. XlOO (After Haeckel) (From Kiihn). 



Genus Acanthociasma (Fig. 103, h) 



Radial spines few, arranged according to Muller's law; without tangential 

 skeletons Legion 2 Acanthometrida 



