The Sarcodina 213 



ous skeletal elements are the rule. Rods and spines, if present, always 

 lie outside the capsule. In addition to rod-like elements, or in their 

 absence, one or more lattice-work layers may be deposited, peripheral 

 to, and concentric with, the central capsule. The lattice framework may 

 be spherical or non-spherical (bell-shaped, helmet-shaped, etc.), and in 



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Fig. 5. 9. A. Acanthometra pellucida, showing central capsule, axial rods 

 and "myonemes" (myophrisks) joining the superficial cytoplasm and the 

 sheaths of the axial rods; x200 (after Moroff and Stiasny). B, C. Axial rods 

 and myophrisks in Actipylina; ectoplasmic layer expanded and myophrisks 

 contracted (B); ectoplasmic layer contracted and myonemes extended (C); 

 schematic (after Schewiakoff). D. Dorotaspis lieteropora Bernstein, showing 

 lattice-work shell and axial rods; schematic (after B.). 



the latter case may approach bilateral symmetry. Complicated skeletons 

 already had been developed early in the known history of the Radiolarida 

 (Fig. 5. 11, A, B). 



The intracapsular cytoplasm contains the nucleus or nuclei, stored re- 

 serves, pigment granules in some species, and the so-called "yellow cells" 

 in the Actipylina. The number of nuclei varies. The Actipylina are typ- 



