214 Forty-third Report on the State Museum 



S. suborbicularis. Hall. Kinderhook to Keokuk. 

 S. Newberryi, Hall. Upper Waverly. 

 S. striatiformis, Meek. Upper Waverly. 

 S. Grimesi, Hall. Burlington. 

 S. Forbesi, Hall. Burlington. 

 S. imbrex, Hall. Burlington. 

 S. incerta, Hall. Burlington. 

 S. Keokuk, Hall. Keokuk. 

 S. neglecta, Hall. Keoki.ik. 



S. fastigata, Meek & Worthen. Keokuk. (=S. Mortonana, Miller.) 

 S. Logani, Hall. Keokuk. 

 S. rostellata. Hall. Keokuk. 

 S. tenuimarginata. Hall. Keokuk. 

 S. tenuicostata, Hall. Keokuk. 

 S. lateralis, Hall. Keokuk and St. Louis. 

 S. subjequalis. Hall. Keokuk and St. Louis. 

 S. Keokuk var. Hall. S. Littoni, Swallow. St. Louis. 

 S. Leidyi, Norwood and Pratten. St. Louis and Chester. 

 S. bifurcata. Hall. St. Louis. 

 |S. subcardiformis, Hall. St. Louis. 

 S. increbescens. Hall. Chester. 



S. opima, Hall, Eockymontana, Macon. Coal Measures. 

 S. camerata, Morton. Upper Coal Measures. 

 S. Texana, Meek, multigranosa, Worthen. Upper Coal Measures. 



Martinia. 

 S. maia, Billings. Corniferous. 

 S. subumbonata. Hall. Hamilton. 

 S. glaber var contracta. Meek & Worthen. Coal Measures. 



Amboccelia. 

 A. umbonata, Conrad. Hamilton. 

 A. prjBumbona, Hall. Hamilton. 

 A. gregaria. Hall. Chemung. 

 S. planoconvexa, Shumard. Uj^per Coal Measures. 



Sykingothyroid Forms. 

 In this group are included certain forms of Spirifera with simple 

 low plications granulose or papillose surface makings, and show- 

 ing a tendency to develop a callosity, mode or process within, and 

 in advance of, the apex of the foramen; which in its fuller 

 development becomes an extended process or slate and is finally 

 incurved and enrolled forming the characteristic tubular sheath 

 of Syringothyris* 



