FROM NORTHWESTERN EUROPE 35 
developed but not uncommonly it shows varying degrees of asymmetry. There are 
usually 8-9 ribs on the fold. 
Fic. 14. Transverse serial sections of Lacunosella vaga sp. nov. Topotype. Kimmeridgian— 
mutabilis zone. Sermérieu (Isére), France. (3). 
