PLATE 23 



Syringothyris occidentalis (Swallow) 

 Page 103. 



Fig. 1. Mould of pedicle valve. (Collection of D. K. Greger. Photo by Greger. ) 

 (Callaway limestone of Callaway County.) 



Spirifer euryteines Owen 

 Page 100. 



Fig. 2. An unusually flat cardinal area. (Snyder Creek shale of Callaway County.) 

 Fig. 3. An exfoliated pedicle valve. (Mineola of Montgomery County.) 



Spirifer asper Hall 

 Page 100. 



Fig. 4. An enlargement to show details of the sinus. (Photo by Greger.) 

 (Callaway limestone of Callaway County.) 



Pentamerella missouriensis Branson 

 Pege 88. 



Fig. 5. The holotype. (X3J-2). (Snyder Creek shale of Callaway County.) 



Gypidida mineolaensis Branson 

 Page 93. 



Fig. 6. Pedicle valve of an imperfect specimen. 

 Figs. 10 and 11. Side and pedicle views of an imperfect specimen. 

 (Specimens from {he Mineola of Ralls County.) 



A try pa hystrix Hall 

 Page 99. 



Fig. 7. A specimen from the Lime Creek of Iowa to compare with Atrypas from the 

 Snyder Creek shale 



A try pa spinosa Hall 

 Page 98. 



Figs. 8 and 9. Pedicle views of average specimens. 



(Snyder Creek shale of Callaway County.) 



A try pa reticularis (Linnaeus) 

 Page 97. 



Fig. 12. A small smooth sp3cirren, psdicle view. 

 Fig. 13. A large rou^h specimen, ps licle view. 



(Snyder Creek shale of Callaway County.) 



