70 
Rept. Geol. Surv., Indiana, p. 335, Pl. 29, figs. 28-30; Retzia 
verneuiliana Walcott, 1884, Pal. Eureka District, p. 220, PL 7, figs. 
5-5a; Eumetria verneuiliana Hall and Clarke, 1895, Pal. N.Y., vol. 
8, pt. 2, Pl. 51, figs. 13-26, 34, 35, Pl. 83, figs. 26-27; Girty, 1899, 
U.S. Geol. Surv., Mon. 32, p. 560, Pl. 68, figs. 12 a-b; E . marcyi 
Girty, 1904, U.S. Geol. Surv., Prof. Paper 21, p. 49, Pl. 10, figs. 
15-17; Beede, 1906, 30th Ann. Rept. Geol. Surv., Indiana, p. 1319, 
Pl. 22, figs. 28-30; Girty, 1911, U.S. Geol. Surv., Bull. 439, p. 77, 
Pl. 8, fig. 10; E. verneuiliana Weller, 1914, Geol. Surv., Illinois, 
Mono. 1, p. 442, Pl. 76, figs. 18-24. 
Remarks. It seems impossible with the material in hand to divide the 
E. marcyi group as Hall, and lately Weller, have done in the Mississippi 
valley. In number of plications they most closely resemble E. costata 
(Hall); in their slight convexity they approach E. costata and E. vera; 
in size they are similar to E. vera. Since the Minnewanka material is thus 
variable, it seems best to use for them Hall’s earliest name for this type of 
shell, E. marcyi. 
Locality and Horizon. Mississippian of Mississippi valley and west. 
In the Minnewanka region in the Lower Mississippian of sections 2-23 (c) ; 
4-2 (?). 
Genus, Hustedia Hall 
Hustedia circularis (Miller) 
1894. Retzia t circularis Miller, 18th Rept. Geol. Surv., Ind., p. 316, 
Pl. 9, figs. 32-34; Hustedia circularis Weller, 1914, State Geol. 
Surv., 111., Mon. 1, p. 451, Pl, 76, figs. 47-52. 
Remarks. This small shell is apparently identical with the Missouri 
species. The measurements of the latter as given by Weller show a some- 
what thicker shell, but a slight variation in thickness is to be expected in the 
same species. It differs from H. mormoni of the Pennsylvanian, its nearest 
ally, in its smaller size, finer and less angular plications, and proportionately 
broader shell. 
Locality and Horizon. Lower Mississippian of Missouri. In the 
Minnewanka region in the Lower Mississippian of section 2-35 (R). 
Genus, Athyris McCoy 
Athyris angelica Hall 
1861. Athyris angelica Hall, 14th Rept. N.Y. State Cab. Nat. Hist., p. 99; 
ibidem, 1862, 15th Rept., Pl. 3, figs. 10-13, 24; Hall, 1867, Pal. 
N.Y. 4, p. 292, Pl. 47, figs. 9-20; Hall and Clarke, 1893, Pal. N.Y. 
State, pt. 2, p. 90, Pl. 45, figs. 26-30. 
Remarks. The Minnewanka specimens somewhat resemble both 
Athyris angelica Hall from the Chemung of New York and Pennsylvania 
and A . angelica occidentalis Whiteaves from the Devonian of Athabaska river. 
The latter differs from our form in its smaller size; the median sinus of the 
pedicle valve is more marked, being deeper with bounding folds higher 
and narrower and extending to the beak; the brachial valve has a more 
conspicuous and flat-topped median fold, bordered by furrows which begin 
at the umbo, the outer side of these furrows being limited by a secondary, 
more divergent pair of folds; it thus results that the brachial valve has 
