PLATE XIII 
Fig. 1. Modiolopsis orthonota perumbonata Foerste. Right valve. Credit 
Forks, Ontario; Whirlpool sandstone. 
Fig. 2. Modiolopsis orthonota (Conrad). A-E, right valves; F, G, left valves. 
Credit Forks Ontario; Whirlpool sandstone. 
Fig. 3. Ctenodonta (?) creditensis Foerste. Left valve. Credit Forks, Ontario; 
Whirlpool sandstone. 
Fig. 4. Ctenodonta (?) cataractensis Foerste. Left valve. Credit Forks, 
Ontario; Whirlpool sandstone. 
Fig. 5. Ctenodonta (?) sp. Left valve. Credit Forks, Ontario; Whirlpool 
sandstone. 
Fig. 6. Schuchertella creditensis Foerste. Pedicel valve, showing location and 
length of dental lamellae. Credit Forks, Ontario; Whirlpool sandstone. 
Fig. 7. Dahnanella eugeniensis Williams. Brachial valve. Credit Forks, 
Ontario; Whirlpool sandstone. 
Fig. 8 . Whitfieldella circularis Foerste. Brachial valves. Credit Forks, 
Ontario; Whirlpool sandstone. 
Fig. 9. Lingula cf. cuneata Conrad. Brachial valve. Credit Forks, Ontario; 
Whirlpool sandstone. 
Fig. 10. Calymene cf. cedarvillensis Foerste. A, cranidium. B, fragment of 
four segments of thorax. C, pygidium. From residual chert, regarded as belong- 
ing in the Laurel member of the Niagaran, loose on top of Jeptha Knob, in 
Shelby county, Kentucky. 
Fig. 11. Liospira (?) sp. Credit Forks, Ontario; Whirlpool sandstone. 
Fig. 12. Dictyophlois reticulata illinoisensis Foerste. Clay cast of part of sur- 
face of the specimen illustrated on plate XII. 
