218 The Sarcodina 



Dorotaspis Haeckel (Fig. 5. 9, D), Hexaconus Haeckel, Litholopus Haeckel, Lithoptera 

 Miiller, Phractaspis Haeckel, Podactinelius Schroder, Sphaerocapsa Haeckel, and Tlioro- 

 capsis Haeckel. 



Suborder 2. Peripylina. There is a fairly thick spherical central capsule 

 in which numerous pores are uniformly distributed. There is no skeleton 

 at all in some species. In others, a relatively simple skeleton consists of 

 scattered extracapsular spicules, a perforated shell, or both. The lattice- 

 work shells may be single, or in certain families, often multiple in a con- 

 centric series. In CoUosphaera, Collozoum, and Sphaerozoiim the central 

 capsules, instead of separating after fission, remain embedded in a com- 

 mon extracapsular mass to form colonies which may measure several 

 centimeters. 



The following genera have been included in the Peripylina: Acanthosphaera Ehren- 

 berg, Arcliidiscus Haeckel, Cenolarcus Haeckel, CenospJiaera Ehrenberg (Fig. 5. 11, A), 

 Chitoanastrum Haeckel, CoUosphaera Miiller, Collozoum Haeckel (140), Cromyodrymus 

 Haeckel, Cytocladus Schroder, Druppula Haeckel, Euchitonia Haeckel, Lampoxanthiurn 

 Haeckel, Orosphaera Haeckel, Physeiuaticum Haeckel, Pipetla Haeckel, Sphaerozoum 

 Meyen, Staurocyclia Haeckel, Staurosphaera Haeckel, Thalassicolla Huxley (62; Fig. 5. 

 II, D), Thalassolampe Haeckel, Thallasophysa (14), Thalassothamnus Hacker. 



Suborder 3. Monopylina. The thick-walled central capsule (Fig. 5. 12, 

 F), which may be radially or bilaterally symmetrical, shows a single porous 

 plate or, more often, a single field of small pores with thickened walls. 

 The pseudopodia usually arise opposite this field. The siliceous skeleton, 

 composed of solid elements, may show three distinct parts (tripod, capit- 

 ulum, and ring). The basic form of the tripod (Fig. 5. 12, A) suggests 

 the name applied to the structure. The ring, if present, is attached to 

 the tripod (Fig. 5. 12, B). Outgrowths from the ring and tripod may result 

 in a hemlet-shaped shell, the capitulum (Fig. 5. 12, C-E). Modification of 

 these three basic elements, by suppressions or by the addition of append- 

 ages and decorations, gives rise to a variety of skeletons. 



The suborder includes the following genera: Cortiniscus Haeckel, Cystidium Hert- 

 wig, Dictyophimus Ehrenberg (Fig. 5. 12, E), Eucyrtidium Haeckel (Fig. 5. 12, D), 

 Lithocircus Miiller (Fig. 5. 12, F), Protympanium Haeckel, Stichoformis Haeckel, 

 Theopera Haeckel, Theophormis Haeckel, Triplagia Haeckel, Zygostephanus Haeckel. 



Suborder 4. Tripylina. The central capsule has one major (the astro- 

 pyle) and two accessory openings (parapyles), the latter usually lying 

 opposite the first (Fig. 5. 13, A). The astropyle typically is covered with 

 a striated plate, in which the central openings are often drawn out into 

 tubes. A characteristic feature is an accumulation of greenish-brown mate- 

 rial (perhaps the reinnants of diatoms and other food) just outside the 

 astropyle. This colored material ("phaeodium") is responsible for the 

 name, "Phaeodaria," often applied to this suborder. 



The siliceous skeletons show a wide range in complexity. The skeletons 



