PALAEONTOLOGY 



MAGELLANIN/t 

 (Austral) 



Magellania 

 (Cainoioic -Recent) 



Terebratella 

 (Jurassic -Recent) 



Meaerlina 

 (Recent) 



MEGATHYRIN/C 



Megath/ris [Argiope] 

 (Jurassic Recent] 



Cislella 

 (CreUceous-Recentj 



DALLININ/E 



(Boreal) 



Dallina 

 (Cainozoic-Reccnt) 



Trigonosemus 

 (Cretaceous) 



Muhlfeldtia 

 (Jurassic-Recent) 



Ismenia 

 (Jurassic) 



Platidia. 

 (Recent) 



Zellania 

 (Jurassic) 



FIG. 10. EVOLUTION OF THE LOOP IN LONG-LOOPED 

 TEREBRATULACEA. 



Loop in outline, septum black. (After Beecher.) 



