53 
Remarks. This variety is merely a centronatus greatly extended 
laterally, but lacking the submucronate cardinal extremities of the latter; 
activity of growth in this direction tended to lessen the depth of the sinus 
and resulted in less abrupt lateral slopes. In all other respects — character 
of plications, their method of branching in sinus and on fold, curvature, 
areas, etc. — it is a typical centronatus. This varietal offshoot occurred 
during the acme of the development of Spirifer centronatus. 
Locality and Horizon. In the Minnewanka region in the Lower Missis- 
sippian of section 2-24 (c), 25 (r). 
Spirifer missouriensis Swallow 
1860. Spirifer missouriensis Swallow, Trans. St. Louis, Acad. Sci., vol. 1, 
p. 643; Weller, 1914, 111. State Geol. Surv., Mon. I, p. 319, PI. 39, 
figs. 11-23. 
This species seems to be slightly represented among the Minnewanka 
specimens. A small brachial valve is 8 mm. long, 11 mm. wide along the 
hinge-line, and about 2 mm. in convexity. The narrow, low, median fold 
has four plications; these entering as a single one at the beak increase by 
bifurcation; the two middle ones occupy the crest of the fold, and upon 
each side of this fold the lateral surface of the valve is occupied at the 
frontal margin by 13 plications; these latter are somewhat fasciculate; 
from the fold outward these groups consist of 3, 3, 3, 2, 1, 1, plications; 
the furrows between the groups of fascicles are deeper than between the 
members of a fascicle, but each fascicle, because of the middle plication 
being only slightly, if at all, elevated above the others, lacks the indiv- 
iduality, the distinctness, of S. cameratus. The entire surface is covered 
with radiating striae. Our specimens appear to agree fully with those 
figured and described by Weller. 
Locality and Horizon. Lower Mississippian of Missouri. In the 
Minnewanka region in the Lower Mississippian of section 4-3 (r). 
Spirifer newberryi Hall 
1883. Spirifera newberryi Hall, Kept. N.Y. State Geol. for 1882, PI. (31), 
56, figs. 9, 10; Spirifer newberryi Hall, 1894, 13th Ann. Kept. N.Y. 
State Geol., p. 649; Hall and Clarke, 1895, Pal. N.Y., vol. 8, pt. 2, 
p. 362, PI. 31, figs. 9, 10; Hall, 1897, 14th Kept. N.Y. State Geol., 
p. 357, PI. 7, figs. 25, 26. 
Remarks. The single specimen found agrees fully with the figure and 
very brief description given of this species by Hall. The figure is that of a 
brachial valve slightly larger than ours; the fine radiating striae figured 
are duplicated upon our specimen. 
Locality and Horizon. Mississippian of Ohio. In the Minnewanka 
region in the Mississippian of section 2-22 (R). 
