PLATE 29. 



Page 

 Figs. 1-8. Spirifera oweni 197 



1. Dorsal view of a young specimen. 



2. Dorsal view of a larger individual. 



8-7. Dorsal, ventral, cardinal, profile and front views of a specimen of ordinary size and char- 

 acteristic form. 



8. Interior of a part of a ventral valve. 



Fig. 9 - 18. Spirifera acuminata 198 



9. Front view of a young individual, from New York. 



10 - 18. Dorsal, ventral, cardinal and profile views of a specimen of ordinary size and form, 

 from near Sandusky, Ohio. 



14. Front view of a small but extremely elevated specimen, from Williamsville, N. Y. 



16. Cast of a ventral viilve, showing the muscular impression of greater width than usual; from 

 Albany county. New York. 



16, 17. Ventral and cardinal views of a cast in chert, from Camp Creek, Ind., showing muscu- 

 lar impressions, dental cavities, etc. The mesial elevation has been injured by weather- 

 ing, and the outline shows the probable extent of the elevation. 



18. Dorsal view of a specimen from the same locality as the preceding, showing the peculiar 

 muscular markings of the dorsal valve. 



