Atrypae of the Central Missouri Devonian 49 
PLATS Ick. 
Figs. 1—5 Artypa dovoniana V Jebster 
1. Anterior view of an average wes Be Pedicle views 
of two well preserved specimens. 4, Anterior views of two 
young shells, both showing the icraetese U' shaped sinus. 
Figs. 6—8 Atrypa rockforde nsis Webste 
6. Brachial view of an average shell. . Pedicle view al a crushed 
gerontic shell, note the thickened margins. 8. View of a well 
presented brachial valve. 
Figs. 9—l1 <Atrypa acne gst se 
9. Pedicle view of the largest speci colle 
view of the shell. 11. Brachial causett "of ao 
jet : 
ted. 10. "Anterior 
