Skin with rounded scales or spines, or both; rear projections plain 

 Chaetonotus Ehrenberg 



5. Apparently permanently attached or in colonies or living in a tube 6. 

 Temporarily attached or separate, free-swimming or creeping individuals; 



almost always without a tube 15. 



6. In spherical colonies 7. 

 Not so 9. 



7. Colonies free-swimming 



Conochilus Ehrenberg 

 Colonies attached 8. 



8. Animals embedded in a mass of jelly 



Lacinulana Schweigger 

 Not so 



Sinantherina Bory 

 (Megalotrocha Ehrenberg) 



9. No cilia or setae around the corona, although sometimes a ring of cilia 



around the body below the corona 10. 



With cilia or setae around or on the corona 1 1 . 



10. Body fat and sac-like; corona cup-shaped 



Cupelopagis Forbes 

 (Apsilus Metschnikoff ) 

 Body narrow; corona with one long, sickle-shaped lobe 

 Acyclus Leidy 



11. Usually with long bristles, instead of cilia, which move slowly instead 



of beating rapidly like ordinary cilia 12. 



With cilia in two rings around the corona, those of the inner ring 



longer 13. 



12. Corona in the form of iive long, slender projections bearing bristles 



Stephanoceros Ehrenberg 

 Corona plain or lobed, but not drawn out into slender projections 

 Collotheca Harring 

 (Floscularia Oken) 



13. With three or four lobes in the corona 



Floscularia Cuvier 

 (Melicerta Schrank) 

 Corona nearly circular or in two lobes 14. 



14. Corona almost circular 



Ptygura Ehrenberg 

 {Oecistes Ehrenberg) 

 Corona with two very distinct lobes 

 Limnias Schrank 



15. Animal almost or quite spherical, without a foot 



Trochosphaera Semper 

 Not so 16. 



16. With a lorica (or stiff or rigid and usually transparent sheath) 17. 

 No lorica 39. 



66 



