The Sarcodina 219 



Fig. 5. 13. A Central capsule of Trip)lina, showing inner and outer 

 layers, astropyle, two parapyles, and large nucleus; diagrammatic (after 

 Gamble). B. Bivalve shell and its appendages, galea with nasal process, or 

 rhizocanna; astropyle drawn out into a tube; diagrammatic (after 

 Gamble). C. Costanidiuin sol Hacker, portion of skeleton showing lattice- 

 work shell and radial elements; diameter of shell, 400-500^ (after H.). D. 

 Skeleton of Challengeron armatum Borgert, xl70 (after B.). 



of Aulacantha and related genera consist of separate elements, hollow 

 radially arranged rods and sinaller tangentially distributed spicules. The 

 latter are often replaced by a lattice-work shell (Fig. 5. 13, C, D); or two 

 shells may be present, one just outside the central capsule. In some genera, 

 only the inner shell is developed. Several families show a bivalve inner 

 shell (Fig. 5. 13, B), and each valve sometimes bears a hollow apj^endage, 

 the galea. 



The group includes the following genera: Aulacantha Haeckel (13), Aulosphaera 

 Haeckel, Cannosphaera Haeckel, Castanidium Haeckel (Fig. 5. 13, C), Challengeron 

 Haeckel (Fig. 5. 13, D), Circoporus Haeckel, Coelacantha Hertwig, Coeloden- 

 drum Haeckel, Coementella Borgert, Conchoceras Haeckel, Euphysetta Haeckel, 

 Medusetta Haeckel, Tuscarilla Haeckel, Tuscarora Murray. 



CLASS 2. RHIZOPODEA 



These Sarcodina may have lobopodia, filopodia, or myxopodia but 

 do not develop axopodia and do not show a foamy peripheral cytoplasm. 

 Tests, well developed in certain groups, may be composed mainly of 

 organic material, with or without added foreign particles, or largely of 



