110 THE PROTOZOA 



Subclass III. RADIOLARIA. Marine forms of Sarcodina, similar to Heliozoa in 



having ray-like pseudopodia (axopodia and myxopodia), but provided with a 



chitinous capsule which incloses the nuclei. They may or may not have a 



skeleton ; when present the skeleton is formed of acanthin or of silica. The 



group is subdivided into 4 legions, 20 orders, 85 families, 739 genera, and 4318 



species. (Haeckel, 1885.) 

 Legion I. SPUMELLAEIA (or PERIPYLEA) . The central capsule is perforated 



by numerous fine pores. A skeleton may or may riot be present. 

 Order 1. COLLOIDIDA. Without skeleton. Families: Thalassicollidae (solitary 



forms) ; Collozoidae (colonial). 

 Order 2. BELOIDIDA. The skeleton consists of loose silicious needles. P'amilies: 



Thalassosphaeridae (single); and Sphaerozoidae (colonial). 

 Order 3. SPH.ZEROIDIDA. The skeleton consists of from one to many concentric 



globular shells. Families : Liosphaeridae (single) ; Collosphaeridae (colonial) ; 



Stylosphaeridae (single) ; Staurosphaeridae (single) ; Cubosphaeridae (single) ; 



Astrosphaeridae (single). 

 Order 4. PRTJNOIDIDA. With ellipsoidal to cylindrical latticed shells and similar 



central capsule. Families : Ellipsidae ; Druppulidae ; Sponguridae ; Artiscidae ; 



Cyphinidae ; Panartidae ; Zygartidse. 

 Order 5. DISCOIDIDA. Shell and central capsule are discoidal or lenticular. 



Families : Cenodiscidae ; Phacodiscidae ; Coccodiscidae ; Porodiscidae ; Pylodis- 



cidae ; Spongodiscidae. 

 Order 6. LARCOIDIDA. The skeleton is irregularly lenticular or discoid. Families: 



Larcaridas ; Larnacidae ; Pylonidae ; Tholonidse ; Zonaridae ; Lithelidae ; Streb- 



lonidae ; Phorticidae ; Soreumidae. 

 Legion 2. ACANTHARIA (or ACTIPYLEA). The skeleton is formed of acanthin 



arranged in radiating spines, usually twenty in number. 

 Order 7. ACTINELIDA. The spines are more than twenty in number. Families: 



Astrolophidse ; Litholophidas ; Chiastolidae . 

 Order 8. ACANTHONIDA. With twenty spines arranged according to Muller"s 



law (four equatorial, eight tropical, and eight polar) . Families : Astrolonchidae ; 



Quadriloncbidae ; Amphilonchidae. 

 Order 9. SPHiEROPHRACTIDA. With twenty equal quadrangular spines and a 



complete, fenestrated shell. Families : Sphaerocapsidae ; Dorataspidae ; Phrac- 



topeltidae. 

 Order 10. PRTJNOPHRACTIDA. With ellipsoidal, flat, or double-coned shell, 



through which twenty spines radiate according to Muller's law. Families : 



Belonaspidae ; Hexalaspidae ; Diploconidae. 

 Legion 3. NASSELLARIA (or MOWOPYLEA). The skeleton is silicious and 



rarely absent. The central capsule has a single, limited, perforated area at one 



pole ; the extracapsular plasm has no pigment. 

 Order 11. NASSOIDIDA. Monopylaria without a skeleton. Families: Nasselidae. 

 Order 12. PLECTOIDIDA. A complete latticed shell is never formed, but the skele- 

 ton consists of three or more spines radiating from one point below the central 



capsule, or from a central rod. Families: Plagonidae ; Plectanidae. 

 Order 13 STEPHOIDIDA. The skeleton consists of one or two fused rings which 



may be connected by a loose network. Families : Stephanidae ; Semantidae ; 



Coronidae ; Tympanidae. 

 Order 14. SPYROIDIDA. The skeleton consists of a single sagittal ring and a 



latticed shell which is furrowed in the sagittal plane. Families : Zygospyridae ; 



Th'olospyridae ; Phormospyridae ; Androspyridae. 

 Order 15. BOTRYOIDIDA. The skeletons are similar to the preceding, but orna- 

 mented by one or more wing-like processes. Families : Cannobotryidae ; Litho- 



botryidae ; Pylobotryidae. 



