NEOCENE STRATIGRAPHY. 33 1 



jilosa and Crepidula -prcerit^ta occur only at the bottom 

 of the section, the Cre^idtUa grandis. Area niicrodona, 

 Cardium meekianuni, Saxodonius gibbosics, Mactra (not 

 Venus) pajaroensis and Scutella interlineata disappear at 

 different horizons and are replaced in the uppermost lay- 

 ers by living forms. Thus for example the living Echi- 

 narachinus excentricus replaces Scutella interlineata, Car- 

 dium corbis replaces C. meekianum, from which it probably 

 descended, etc. 



The fauna of the main body of the section is as fol- 

 lows: 



