Plate 14. 



1. Poecillastra tricornis. From a section tangential to surface, showing flagellated 



chambers with Sollas's membrane ; c. iv., canal wall ; 

 X 250. 



2. " " Streptasters ; a, spiraster from dermal membrane ; c, paren- 



chymal metaster ; h, d, parenchymal spirasters ; x 600. 



3. " " From a radial, vertical section, showing oscular surface, 



with an oscular depression, through the aperture at the 

 bottom of wliich a shell of a Foraminifera is partially 

 protruded. Below oscular membrane and aperture an 

 incomplete septum extends across the canal; x 30. 



4. " " From a radial, vertical section, showing pore surface. 



Fore membrane, forming bottom of a very sliallow con- 

 cavity, is produced into a plug-like process. Axis of 

 this is marked by dense streak of spirasters, representing 

 the closed pore. Side wall of canal, into wliich pore 

 opens, is shown in perspective and exhibits apertures 

 leadiug into branch canals. Canal wall bears some 

 incomplete septa. Lowest and thickest septum is per- 

 forated by a small aperture, in immediate neighborhood 

 of which is a collection of debris, largely shells of 

 Foraminifera; x 30. 



5. " " Pore surface. One pore area with nearly closed pore 



shown. Surface preparatiou ; x 30. 



6. " " Oscular surface. Three oscular membranes, one with open 



aperture, shown. Surface preparation ; x 30. 



7. " " From a radial, vertical section, showing oscular surface. 



A single oscular depression, floor of which constitutes 

 the oscular membrane, is shown. Osculum itself closed. 

 Canal to which osculum belongs exhibits on its lateral 

 wall apertures of branches, and is crossed by perforated 

 septa; x 30. 



8. " " Oscular surface ; from a photograph ; \. 



9. Poecillastra crihraria. Cladome of triaene, from above ; two rays branched ; x 70. 



10. " " Characteristic triaene, from the side ; x 70. 



11. " " Microxea; x 250. 



12. " " Streptasters : a, spiraster from dermal membrane ; h, 



plesiaster from ])arencliyma; c, d, plesiaster-metasters 

 from parenchyma; x (iOO. 



