344 BIOLOGY OF THE PROTOZOA 



Sub-order 1. Sphserellaria, Haeckel. 



Small forms with a rather complex latticed skeleton or closely 

 associated single elements, always of silica. 



Family 1. Sphseroidae, Haeckel. —The skeleton is latticed and may 

 be multiple and concentric as in Cenosphsera or Staurosphsera. 

 Skeletons and central capsules globular. 



FamUy 2. Prunoidae, Haeckel.— The skeleton elements are similar 

 to those of the preceding family but the organisms are ellipsoidal 

 by reason of the elongation of the vertical axis of central capsule 

 and skeleton. 



Family 3. Discoidse, Haeckel.— These are flattened and lens-like 

 or the reverse of the axial relations of the preceding family, Init with 

 similar skeletons. 



Family 4. Larcoidae, Haeckel.— These forms are similar to the 

 Prunoidae in having the vertical axis longer than the horizontal, 

 but the organisms are flattened "dorso-ventrally." 



Sub-order 2. Polycyttaria, Haeckel. 



When mature these organisms are colonial, the colonies often 

 several centimeters in length and ellipsoidal, spherical, or band-form 

 in shape. A great number of central capsules are embedded in a 

 common protoplasmic mass, the capsules being increased by division 

 or budding (Brandt). It is in connection with these forms that 

 the most satisfactory observations have been made on swarm-spore 

 formation. Here in some genera large and small swarmers (macro- 

 and microspores) are formed by difl'erent individuals, and this has 

 led to the inference that they may be macro- and microgametes 

 although proof is lacking. In some species, e. g., CoUosphoera 

 huxleyi, macrospores are formed in one hemisphere and microspores 

 in the other hemisphere of the same central capsule. In this sub- 

 order also, ZooxanthcUce, or yellow cells, are common. 



Family 1. Sphserozoidae, Haeckel. Great colony forms without 

 latticed skeletons but frequently with isolated tangential spicules 

 of silica (Collo'oiim, Sphoerozonm) . 



Family 2. CoUosphaeridae, Joh. Miiller.— Forms in which each 

 central capsule is enclosed in a single latticed silicious skeleton 

 {Collosphwra). 



Sub-order 3. Collodaria, Haeckel em. Brandt and Haecker. 



These are solitary Peripylea with greatly developed extracapsular 

 plasm and are usually confined to surface waters. They are usually 

 spherical with no skeleton at all or with skeletons of the simplest 

 type. They are uninucleate, with nuclei of complex structure. 



