PLATE 30. 



Page 

 Figs. 1-9. Spirifera raricosta 192 



1. A dorsal view of a young specimen. 



2. A dorsal view of a larger individual preserving a portion of the shell. 



8-6. Dorsal, ventral, profile and front views of a specimen which is very short upon the hinge 

 line and of very gibbous form, with less than the nsuiil number of plications. 



7. A ventral valve which is very much extended pn the liinge line, presenting much the appear- 



ance of S. perlamellosa. 



8. A front view of a specimen, showing the elevation of the fold. 



9. The interior of a ventral valve which is much rounded on the cardinal extremities. 



Figs. 10 - 15. Spirifera disparilis 204 



Compare with S. pyxadatus, of the Oriskany sandstone. 



10- 12, 14. Dorsal, ventral, prolile and front views of a sp.,>cinien of ordinary character. 

 13. Cardinal view of another individual, showing the area and foramen. 



15. Dorsal view of a larger .specimen, showing stronger lateral plications. The figures are all 



enlarged to two diameters. 



Figs. 16 - 20. Spirifera mac rothtris 202 



16. Dorsal view of a large specimen showing the area and foramen of the ventral valve. The shell 



is almost entirely removed, leaving a partial cast on the dorsal side. 



17. A large imperfect ventral valve. 



18. A cardinal view of another specimen, showing the foramen and the striated cardinal area. 



19. Cardinal view of a young individual, showing a more elevated and sharper mesial fold. 



20. A partial ca-st of the ventral valve, showing the filling of the large muscular imprint. 



Fig. 21. Spirifera UNXCA 203 



21. An imperfect ventral valve. There is a strong probability that this is identical with S. 



areno$a, of the Oriskany sandstone. 



