82 
Remarks. The above measurements were made by adding the last 
whorl of one individual to another shell as the smaller form seemed in 
every way to be the immature representative of the larger. Both are 
figured. This is an abundant form but it is quite brittle in its limestone 
matrix. The shell appears to be an L. shumardanum (Winchell) 1 of the 
Kinderhook of Iowa up to the last one or two whorls; the surface markings 
of the latter are unknown. If WinchelPs species is not founded upon 
an immature shell our form must be distinct because of its great size, 
if because of no other distinction. L. shumardanum has a height of 14 
mm., with a last whorl 6 mm. high; it has six or seven whorls and an apical 
angle of 34 degrees. Specific name derived from the Rocky mountains, 
in which it occurs. 
Locality and Horizon. In the Minnewanka region in the Mississippian 
of sections 2-25 (c), 26 (R). 
Genus, Platyceras Conrad 
Platyceras par alius White and Whitfield var. 
1862. Platyceras paralium White and Whitfield, Proc. Boston Soc. Nat. 
Hist., vol. 8, p. 302; Capvlus par alius Keyes, 1894, Missouri 
Geol. Surv., vol. 5, p. 174, PL 53, figs. 1 a-d; Weller, 1901, Trans. 
Acad. Sci., St. Louis, vol. 11, p. 201, PI. 20, figs. 13-14. 
Remarks. One imperfect specimen resembles rather closely the form 
illustrated by Weller in figure 14 2 as a variety of P. paralius. It also 
resembles Keyes’ figures 1 b-c 2 which he calls immature specimens of 
this species. It is also closely similar to Girty’s Platyceras form E,* 
except that our form expands more rapidly and has a slightly greater 
incurvature. The apex is rather closely incurved and the radiating folds 
are indistinct though present. Shell angular on the dorsum, especially 
towards the apex, much less angular towards the aperture. Shell more 
inflated upon the right side than upon the left. 
Locality and Horizon. In the Lower Mississippian of Mississippi 
valley. In the Minnewanka region in the Lower Mississippian of section 
2-25 (R). 
Genus, Paleocapulus Grabau and Shimer 
Paleocapulus equilatera (Hall) 
1860. Platyceras equilatera Hall, Supp. vol. 1, pt. 2, Geol. Rept., Iowa, 
p. 89; Meek and Worthen, 1873, Geol. Surv., Illinois, vol. 5, p. 518, 
Pl. 17, fig. 2; White, 1881, Dep. State and Geol., Indiana, 2d, 
Ann. Rept., p. 514, PL 7, fig. 5; Capulus equilateralis Keyes, 1894, 
Geol. Surv., Missouri, vol. 5, p. 178, PL 52, figs. 10 a, b. 
Remarks . This is the most abundant gastropod in the Mississippi 
of this region. The shells described under this name from Illinois by 
Meek and Worthen 4 have a length and breadth of 40 mm. and 29 mm., 
respectively. 
1 Trans. Acad. Sci., St. Louis, vol. 10, p. 106, PI. 7, fig. 6. 
*Loo.cit. 
* U.S. Geol. Surv., Mon. 32, pt. 2, p. 576, PI. 66, figs. 11 a-d. 
* Loc. tit. 
