PLATE XXXVII. 



(Figs. 1-12,26-31 bj- U. I". WHiriiKi-i); 13-15,18, 19, 23, 24 by E. Emmons; 16,17,20-22, 25, 32, 33 by G B. SiMi'SON.) 



Genus SPIRIFER, Sowkkhy. 



Pufc'O 1. 



SPIKIFEli NlAOAUENSIS, CoiUad. 

 See Plale 21. 

 Fig. 1. An enUrg-eil view of the deltiilial i-egpion of the pedicle-valve ; showing the uncompleted growth 

 of the deltidial plates. 



Niagara shales. Western New York. 



Spirifeu nobu-is, 15:iri;iii(l('. 



Fig.s. 2, 3. Opposite sides of an internal cast ; showing the coarse, duplicating pli<-ations, the impressions 

 of strong dental lanudhe and a low median ridge in the jiedicle-valve. 

 Niagara dolomites. Racine, Wisconsin. 



Spirifer mesastkialis, Hall. 



Fig. 4. The exterior of a brachial valve, with highly extended cardinal extremities. 



Fig. 5. The brachial valve of a specimen much shorter on the hinge. Both specimens show the fine slria- 

 tion of the median fold. 



Chemung gi-oup. /Southwestern New York. 



Spiuifeu Tullius, Hall. 



Figs. 6, 7. Views of .an avei-age specimen. The tine radial lineatiun of the surface is not shown in the 



figures. 



Hamilton shales. Skaneateles, N. Y. 



Spibifer sculptilis. Hull. 



Fig. 8. Exterior of a pedicle-valve ; showing the strong, distant laniell.'e. 

 Hamilton group. Western New York. 



Spirifeu con.^op.uixus d'Orliigiiy (=S. zic-zac. Hall). 

 See Plate 'M. 

 Figs. 9, 10. Views of both valves of a normal example ; showing the sharp plications and the closely 

 crowded concentric lamelliE. 



Hamilton group. Canandaigua Lake, N. Y. 



Spikifkr gregarius, Clapp. 



Figs. 11, 12. Two views of an average specimen ; showing the short hinge, prominent umbo, and the bioad, 

 deep sinus of the pedicle-valve. 



Corniferous limestone. Falls of Vie Ohio. 



Spirifer Keokuk, Hall, var. ? 



Figs. 13-15. Views of a silicitieil shell, with sharp lateral plications, and low duplicate median plications on 

 the fold and sinus. 



St. Louis group. Southern Indiana 1 



Spirifer Tex anus. ^Icck. 



Figs. 16, 17. Views of a rather small specimen'; showing the short hinge, nlnugate form .-uid highly arched 

 umbo of the pedicle-valve. 



Carboniferous limestone. Graham county, Texa.'i. 



