PLATE XXXVII. 
(Figs. 1-12, 26-31 by 11. P. WHITFIELD; 13-16,18, 19, 23, 21 by'E. Emmons; 16, 17, 20-22, 25, 32, 33 by G, B. SlMl’SON.) 
Genus SPIEIFER, Sowerby. 
Page 1. 
Spirieer Niaoarensis, Conrad. 
See Plate 21. 
Fig. 1. An enlarged view of the deltidial region of the pedicle-valve ; showing the iincoinpleted growth 
of the deltidial plates. 
Niagara shales. Western New York. 
Spirifer nobilis, Barraiide. 
Fig.s. 2, 3. Opposite sides of an internal cast; showing the coarse, duplicating plications, the impressions 
of strong dental lamellse and a low median ridge in the pedicle-valve. 
Niagara dolomites. Racine, Wisconsin. 
Spirifer mesastrialis, 
Fig. 4. The exter ior of a bi-achial valve, with highly extended cardinal extremities. 
Fig. 5. The brachial valve of a specimen much shorter on the hinge. Both specimens show the fine stria- 
tion of the median fold. 
Chemung gi'oup. Southwestern New York. 
Spirifer Tullius, ILill. 
Figs. 6, 7. Views of an average specimen. The fine radial lineation of the sui-face is not shown in the 
figures. 
Hamilton shales. Ska^ieateles, N. Y. 
Spirifer sculptills, Ilidi. ’ 
Fig. 8. Exterior of a pedicle-valve ; showing the sti’ong, distant lamellie. 
Hamilton group. Western New York. 
Spirifer con.sobrinus d’Orhigny (=S. zic-zac, IL-ill). 
See Plate 34. 
Figs. 9, 10. Views of both valves of a noi-mal example ; showing the shar[) plications and the closely 
crowded concenti-ic lamell*. 
Hamilton gi-oup. Canandaigua Lake, N. F. 
Spirifer gregarius, Chtpp. 
Figs. II, 12. Two views of an avei'age specimen ; showing the short hinge, prominent umbo, and the broad, 
deep sinus of the pedicle-valve. 
Corniferous limestone. Falls of the Ohio. 
Spirifer Keokuk, Hall, var. ? 
Figs. 13-15. Views of a silicified shell, with shai'p lateral plications, and low duplicate median plications on 
the fold and sinus. 
St. Louis groiRi. Southern Indiana ? 
Spirifer Texanus. Meek. 
Figs. 16, 17. Views of a rather small specimen^; showing the short hinge, elongate form and highly arched 
umbo of the pedicle-valve. 
Carbonifei’ous limestone. Graham county, Texas. 
