83 
Our form seems to be identical in all respects with the Mississippi 
Valley form. 
Locality and Horizon . ■ Lower Mississippian of Mississippi valley. 
In the Minnewanka region in the Mississippian of sections 2-23 (C), 
24 (c); 4-2 (c), 3 (?). 
Genus, Orthonychia Hall 
Orthonychia acutirostris (Hall) 
1856. Capulus acutirostris Hall, Albany Inst., Trans., vol. 4, p. 31; Hall, 
1858, Iowa Geol. Surv., Ann. Kept., vol. 1, pt. 2, p. 665, PI. 23, 
figs. 14 a, b; Platyceras uncum Meek and Worthen, 1873, Illinois 
Geol. Surv., vol. 5, p. 516, PI. 17, fig. 1; P, acutirostris Hall, 1883, 
Indiana Dept. Geol. and Nat. Hist., 12th Ann. Rept., p. 370, PL 31, 
figs. 13-15; Orthonychia acutirostre Keyes, 1895, Missouri Geol. 
Surv., vol. 5, p. 190, PI. 54, figs. 2 a-c; {Orthonychia acutirostre ) 
Cumings, 1906, Indiana Dept. Geol. and Nat. Res., 30th Ann. 
Rept., p. 1335, Pl. 25, figs. 13-15. 
Remarks. Our two specimens appear to be identical with the species 
as developed in the Mississippi valley. 
Locality and Horizon. Lower and Middle Mississippian (Keokuk- 
St. Genevieve) of Mississippi valley. In the Minnewanka region in the 
Mississippian of section 2-23 (r). 
Orthonychia cyrtolites (McChesney) 
1860. Platyceras cyrtolites McChesney, Desc. New Pal. Foss., p. 71; 
Orthonychia cyrtolites Keyes, 1894, Missouri Geol. Surv., vol. 5, 
p. 188, Pl. 53, fig. 15. 
Locality and Horizon. Lower Mississippian (Burlington) of Mississippi 
valley. In the Minnewanka region in the Mississippian of section 2-23 (R) . 
Genus, Igoceras Hall 
Igoceras subplicatum (Meek and Worthen)? 
1866. Platyceras (Orthonychia) subplicatum Meek and Worthen, Proc. 
Acad. Nat. Sci., Phil., p. 265; Meek and Worthen, 1868, Geol. 
Surv., Illinois, vol. 3, p. 457, Pl. 14, figs. 4 a-c. 
Remarks. A single specimen, slightly crushed laterally, is provi- 
sionally identified with this species. It is a small, conical shell, 6 mm. 
high, rapidly expanding from the excentric beak. There are three well 
marked folds anteriorly and indications of two other obscure ones upon 
each side of the shell. The anterior folds are more prominent in the speci- 
men because of the lateral crushing. Fine growth lines encircle the shell; 
these become stronger toward the aperture. 
Locality and Horizon. Upper Mississippian of the Mississippi valley. 
In the Minnewanka region in the Lower Pennsylvanian of section 1-29 (R). 
