Fig. 8. — Diagram of Kelestoma gradatum. sp. nor. x about 



133 diameters. 



Lacuna in interceeial secondary tissue. 

 Distal shield of secondary aperture. 



Secondary aperture. 



Avicularium. 



Lacuna in secondary tissue. 



Broken end of proximal apertural spine 



Fusion oi proximal apertural spine with 

 distal forks of apertural bar. 



Proximal apertural spine. 



Slot-like gap between proximal apertu- 

 ral spine and distal fork of apertural 



Distal fork of apertural bar. [bar. 



Proximal fork of apertural bar. 

 Costa. 



Pelmatidium. 

 Median area of fusion. 



Interceeial secondary tissue. 



Lacuna in interceeial secondary tissue. 



Fig. 9. — Diagram of the distal end of the cerium of a hypothe- 

 tical Primitive Morphasmopora. Very much enlarged. 



Lacuna in circum-apertural secondary tissue. 



Aperture. 



Distal exalted avicularium. 



Proximal lowly avicularium. 



Lacuna in secondary tissue. 

 Proximal apertural spine. 



Distal fork of apertural bar. 



Proximal fork of apertural bar. 

 Lacuna in secondary interceeial tissue. 

 Costa. 



