256 



THE PROTOZOA 



Legion 3 : Sphcerozoa sen Polycyttaria. Colonial forms consisting of 

 numerous individuals embedded in a common jelly ; their central capsules 

 are distinct, but their extracapsular regions anastomose. The colonies reach 

 a length of several centimetres. Two families. Example : Collozoum. 



SUBORDER II. : ACANTHARIA. Skeleton composed of strontium sulphate, 

 typically in the form of spicules radiating from the centre of the body, within 

 the central capsule ; in addition lattice-work shells may be developed. Central 

 capsule with pores evenly developed, or grouped in areas. 



A number of families are recognized, grouped in different ways by different 

 authorities. Example : Acanthometra (Fig. 105). 



\ 



Fia. 109. Eucyrtidium cranioides, Haeckel : entire animal as seen in the living 

 condition. The central capsule is hidden by the beehive- shaped siliceous 

 shell within which it is lodged. From Gamble, magnified 150. 



I. : MONOPYLARIA SETT NASSELLAKIA. Central capsule monaxon 

 in form, with the pores aggregated at one pole into a pore-plate, and the 

 walls of the pores thickened to form a conical structure directed inwards 

 into the central capsule. Several families. Examples : Lithocircus (Fig. 106), 

 Eucyrtidium (Fig. 109). 



SUBORDER IV.: TRIPYLARIA SEU I'H^ODARIA. Central capsule with a 

 principal aperture (astropyle) and two accessory apertures (parapyle). A 

 mass of pigment (phseodium, p 252) surrounds the principal aperture. 

 Divided by Hacker into six legions and numerous families. Example : 

 Aulacantha. 



Bibliography. For references see p. 483. 



