54 
Spirifer striatiformis Meek 
1875. Spirifer (Trigonotreta) striatiformis Meek, Pal. Ohio, vol. 2, p. 289, 
PI. 14, figs. 8 a-e; S. striatiformis Herrick, 1888, Bull. Sci. Lab. 
Denison Univ., vol. 3, p. 44, Pl. 1, fig. 6, PL 3, figs. 23-26, PL 6, 
figs. 6, 7, PL 12, fig. 20; Herrick, 1888, Bull. Sci. Lab. Denison 
Univ., vol. 4, Pl. 2, fig. 9; Herrick, 1895, Geol. Surv., Ohio, vol. 7, 
Pl. 15, fig. 9; Weller, 1914, State Geol. Surv., 111., Mon. 1, p. 364, 
PL 48, figs. 17-21. 
Remarks . The Minnewanka form agrees apparently fully with Meek’s 
type description and figures, and with the recent description of specimens 
from the same locality by Weller; the form, surface markings, and muscle 
impressions within the pedicle valve agree fully. From S . striatus it 
differs especially in lacking the characteristically transverse shell, the 
produced cardinal extremities. 
Locality and Horizon. Lower Mississippian of Ohio and Missouri. 
In the Minnewanka region in the Lower Mississippian of section 2-25 (c), 
29 (C). 
Spirifer rockymontanus Marcou 
Plate VII, figures 4a, b; 5; 6; 7a, b, c; 8; 9; 10 
1858. Spirifer rockymontana Marcou, Geol. N.A., p. 50, Pl. 7, figs. 4-4e; 
S. rockymontanus White, 1877, U.S. Geog. Surv., W. 100th Mer., 
Kept., vol. 4, p. 134, Pl. 11, figs. 9 a-d; Girty, 1903, U.S. Geol. 
Surv., Prof. Paper 16, p. 383, Pl. 6, figs. 4-7 c; Mather, 1915, Bull. 
Sci. Lab. Denison Univ., vol. 18, p. 181, Pl. 12, figs. 1-6. 
Description . Shell of medium size, variable in relation of length to 
breadth. Hinge-line less than, equal to, or greater than, the width of the 
shell below. Dimensions and other characters of various individuals are 
given below; the measurements are in millimetres: 
— 
a 
b 
c 
d 
e 
f 
g 
h 
i 
i 
k 
Length from beak to anterior margin 
15 
14 
21 
28 ± 
17 
18+ 
14 
30 
9 
22 ± 
8 
Length of hinge-line , 
24 
21 
32 ± 
36 ± 
29 
20 
22 
45 ± 
20 
38 + 
14 
Greatest width of shell 
24 
21 
32 ± 
36 ± 
11 
29 
22 
22 
36 
20 
38 + 
16 
Thickness of pedicle valve 
6 
7 
5 
10+ 
11± 
Thickness of brachial valve. 
4 
7 
4 
& 
* ' 4 
Number of plications in sinus or fold at anterior 
margin 
3 
4 
6 
3 
3 
3 
4 
5 
4 
3 
2 
Number of plications upon either side of fold or 
sinus at anterior margin 
10 
10 
10 
9 
10 
10 
8 
9 
9 
10 
9 
Number of plications bifurcating upon either 
side of fold or sinus 
1 
2 
1 
1 
1? 
1 
1 
2 
1 
1 
1 
Hinge-line less (— ), equal to (=), or greater 
than (+), the width of shell below 
+ 
+ 
+ 
Pedicle valve strongly and regularly convex from beak forward; the 
lateral slopes from umbo to cardinal extremities vary from slightly convex 
to somewhat concave, usually they are sigmoid, convex at umbo, becoming 
slightly concave towards the cardinal angles. Cardinal area comparatively 
high, slightly concave, vertically and longitudinally striated, extending to 
