MORPHOLOGY AND TAXONOMY OF THE SARCODINA 459 



asymmetrical. In the former group the aperture is terminal, cir- 

 cular and provided with teeth in Euglypha formed from scales; or 

 the edge of the aperture is smooth or slightly serrated in Spheno- 

 deria. In asymmetrical forms the mouth is subterminal, and 

 oblique in Campascus. The test is retort-shape in Cyphoderia, 

 Campascus and Nadinella. It is pyriform but much compressed in 

 Placocista (without toothed membrane) and Assulina (with toothed 

 membrane about the aperture). In Paulinella the test is Euglypha- 

 like but the cell body possesses a band-form, blue-green, symbiotic 

 alga mistakenly called a chromatophore. In Trichosphaerium, fin- 

 ally, there is no definite test, but the body is enclosed in a gelatinous 

 mantle with radial rods in the asexual generation and without 

 these in the sexual generation. 



Fig. 190. — Difflugia lobostoma; plastogamic stages, formerly interpreted as evidence 

 of conjugation. (From Calkins after Ethumbler.) 



KEY TO ACTINOPODA. 



Pseudopodia with axial filaments (axo- 



podia) Class 1. Actinopoda 



Pseudopodia without axial filaments (myx- 



opodia, filopodia, lobopodia). . Class 2. Rhizopoda 

 Class 1. Marine forms; central capsule present 



Sub-class 2. Radiolaria 1 

 Salt or fresh water forms ; central cap- 

 suit absent Sub-class 1 . Heliozoa 



1 For keys to 4 Legions, 21 Orders, 36+ Families and several hundred genera and 

 species, sec monographs by Hertwig (1879), Haeckel (1887) and Schewiakoff (1926). 



