THE SARCODINA 109 



line or irregular. Some of the higher types have double walls, with supple- 

 mental skeleton and a canal system. 



Subfamily 1. Spirillina. The shell is a flat spiral, without septa; it may be free 

 or attached. Genera: Spirillina Ehbg ('41). 



Subfamily 2. Rotalince. The shell is spiral, rotaliform, and rarely evolute or ir- 

 regular. Genera : Discorbina Lamarck ('04) ; Planorbulina d'Orb. ('26) 

 Truncatulina d'Orb. ('26) ; Anomalina d'Orb. ('26) ; Rotalia Lamarck (1801) 

 Calcarina d'Orb. ('26) ; Patellina Williamson ('58) ; Carpenteria Gray ('58) 

 etc. 



Suborder 4. TINOPORINiE. The shell consists of irregularly heaped chambers, 

 usually with a more or less spiral primordial portion ; a main pseudopodial 

 aperture is usually absent. Genera : Titioporus Carpenter O57) ; Polytrema 

 Risso ('26) ; Gypsina Carter ; Thalamopora Roemer ; Aphrosina Carter. 



Family 10. Nummulinids. The shell is calcareous and finely tubulated; it is 

 typically polythalamous, free, and symmetrically spiral. The higher forms pos- 

 sess a supplementary skeleton and a well-developed canal system. 



Subfamily 1. Fusulinina. The shell is bilaterally symmetrical, with chambers 

 extending from pole to pole, so that each convolution completely incloses the 

 preceding whorl. The septa between the chambers are single as a rule. Genera: 

 Fusulina Fischer ('29); Schwagerina Mbller ('77). 



Subfamily 2. Poly stomellina . The shell is bilaterally symmetrical and nautiloid. 

 The simpler forms are without supplemental skeleton ; the more complex forms, 

 have a skeleton, and canals leading to the outside at regular intervals along the 

 external septal depressions. Genera : Polystomella Lamarck ('22) ; Notiionina 

 d'Orb. ('26). 



Subfamily 3. Nummulitina. ' The shell is lens-shaped or flattened. Genera: 

 Archeodiscus Brady ; Amphistegina d'Orb. ('26) ; Operadina d'Orb. ('26) ; 

 Nunwiulites Lamarck (1801); Heterostegina d'Orb. ('26). 



Subfamily 4. Cycloclypeina. The shell is flat, with a thickened centre, or lens- 

 shaped, and consists of a disc of chambers arranged in concentric annuli with 

 peripheral thickenings. The septa are double, and furnished with a system of 

 interseptal canals. Genera: Cycloclypeus Carpenter ('56) ; Orbitoides d'Orb. 



Subclass II. HELIOZOA. These are naked or shelled forms of Sarcodina of typi- 

 cally spherical form, with but little tendency to change form by amoeboid mo- 

 tion. The pseudopodia, radiating from all parts of the body, are fine and 

 ray-like, rarely changeable, and usually provided with an axial filament. 



Order 1. APHROTHORACIDA. Heliozoa, without a skeleton, but provided with a 

 more or less developed power of amoeboid motion, and with plastic (myxopo- 

 dia) or stiff (axopodia) pseudopodia, the latter possessing axial filaments. 

 Genera: Vampyrella Cienk. ('65); Nuclearia Cienk. ('65); Monobia A. 

 Schneider ('78) ; Myxastrum Haeck. ('70) ; Actinophrys Ehr. ('30) ; Actino- 

 spharium Stein ('57) ; Actinolophns F. E. Schultze ('74)- 



Order 2. CHLAMYDOPHORIDA. Heliozoa, with a soft gelatinous or felted fibrous 

 covering. Genera : Heterophrys Archer ('69) ; Spharastrum Greeff ('73) ; 

 Astrodisculus Greeff ('69). 



Order 3. CHALARATHORACIDA. Heliozoa, with a silicious coating composed of 

 separate and loosely-jointed spicules. Genera : Pompholyxophrys Archer 

 ('69) ; Raphidiophrys Archer ('70) ; Pinacocystis Hert. & Less. ('74) ; Pi- 

 naciophora Greeff ('73) ; Acanlhocystis Carter ('63) ; Diplocyslis Penard ('90) ; 

 Cienkowskya Schaudinn ; Wagiurella Mereschkowsky ('81). 



Older 4. DESMOTHORACIDA. Heliozoa, with a shell of one piece perforated by 

 numerous openings. Stalked or unstalked forms. Genera: Orbulinella Entz 

 ('77) ; Clathrulina Cienk. ('67). 



