PLATE XXII. 



(Figures 1-7, 9-U, 17, 18, 22-24 by R. P. Whitfield; 8, 15, 16. 19-21 by F. B. Meek.) 



LeKend : A. Cardinal area, pedicle-valve. >;. Diductor scai-a. 



t Teeth '^ ■ Socket-walls, 



s'. Median lidge. J- Cardinal process, 



s', s". Callosity in delthyriiim. 1). Dental sockets. 



Gends SPIRIFER, Sowerby. 



Page 1. 



Spikifek Oweni, Hall. 



Fig. 1. Dorsal view of a normal adult. 

 Fig. 2. A protile of the same. 



Fig. 3. The interior of the cardinal portion of a brachial valve ; showing the dental sockets and socket- 

 walls. 

 Fig. 4. A portion of the interior of the pcdicle-valve ; showing the apical callosity, and the scar of the 



diductor mnscles. 

 Fig. 5. A corre.sponding portion of a smaller shell of this species. 



Fig. 6. The interior of the cardinal poi-tion of two valves in articulation, the pedicle-viilve lying beneath. 

 Fig. 7. An enlargement of the surface from a worn specimen. 

 Hamilton group. Clarlie county, Indiana. 



Spibifek Pakkyanus, Hall. 



Fig. 8. The usual form of the shell ; the cardinal area being foreshortened. 

 Fig. 9. An enlargement of the surface chai-actei-s. 



Limestones of the Hamilton group. Davenport, Imva. 

 Fi'rs. 15, 16. Two vievv's of an internal cast. This is the con<lition of the shell which has been known as 



S. capax. Hall. 

 Fig. 17. An enlargement of surface stri.-E, in a worn specimen. 



Sandstones of the Hamilton gi-oup. Mouth of Pine Creek, Iowa. 



Spirifer Makcyi, Hull. 



Fig. 10. A normal individual, from which the cardinal extremities have been broken. 

 Fig. 11. A cardinal view of the same example. 



Fig. 12. The interior of a brachial valve ; showing the articulating apjiaratns. 

 Fig. 13. The interior of a fractured and incomplete portion of the pedicle-valve. 

 Fig. 14. An enlargement of the surface ; showing the elongate, lachrymiform pustules. 

 H.imilton group. Qenesee county, N. T. 



Spikifer Tullius, Hall. 



Fig. 18. The exterior of a pedicle-valve. 



Hamilton shales. Onondaga county, N. T. 



ypIRlFER LIGUS (= SpIRIFER PENNATU.s), OwCll. 



Fig. 19. An adult individual ; showing normal characters. 



Fig. 20. A smaller individual. 



Fig. 21. Cardinal views of articulated valves. 



Figs. 22-24. Enlargements (if the surface, in different conditions of iireservation. Figs. 22 and 24, X 5 ; 



fig. 23 a higher enlargement from a poi-tion of fig. 22, in which the fine radiating surface lines 



are lost. 



Hamilton group. New Buffnlo and Independence, Iowa. 



