PLATE XLI. 
i’. Outer lateral space of area. 
h. Central muscle sear. 
j- Anterior lateral muscle scar. 
p. Pedicle groove. 
v. Visceral cavity. 
vs. Main vascular sinus. 
LINGULELLA (LINGULEPIS) AcUMINATA (Conrad) (p. 545). 
(Pl. XXXIV, figs. 3, 3a-e; Pl. XL, figs. 1, la-s; and Pl. XLII, figs. 1, la-o.] 
Figure 1. Slab figured by Owen [1852, Pl. IB, fig. 8] as Lingula pinnaformis. U.S. Nat. Mus. Cat. No. 17860a. 
Locality 328h, Upper Cambrian sandstone at the falls of the St. Croix, Polk County, Wisconsin. 
la, 1b, and lec. Partly exfoliated ventral valves, showing more or less of the area and interior vascular 
markings. These occur in Locality 82s, Upper Cambrian sandstone at St. Croix Falls, Wisconsin. 
U.S. Nat. Mus. Cat. Nos. 51888a, 51888b, and 51888c, respectively. 
1d and le. Ventral valves associated with the shells represented by figs. la-c. U.S. Nat. Mus. Cat. Nos. 
51888d and 51888e, respectively. 
lf. Dorsal valve associated with specimen represented by figure la. U.S. Nat. Mus. Cat. No. 51888f. 
lg. Dorsal valve associated with the specimen represented by figure la, showing the area and the central 
muscle scars. U.S. Nat. Mus. Cat. No. 51888g. : 
lh. Exfoliated dorsal valve associated with specimen represented by figure la. U.S. Nat. Mus. Cat. No. 
51888h. ; 
li. Ventral valve, from Locality 79b, Upper Cambrian sandstone near Hudson, St. Croix County, Wisconsin. 
U.S. Nat. Mus. Cat. No. 51889a. 
1j, 1k, and 11. Exfoliated dorsal valves associated with the ventral valve sa pseseatie by figure la. U.S. 
Nat. Mus. Cat. Nos. 51888i, 51888j, and 51888k, respectively. 
Im. Dorsal valve associated with the specimen reprecented by figure li. U.S. Nat. Mus. Cat. No. 51889b. 
In. Small exfoliated ventral valve, from Locality 84, Middle Cambrian sandstone at Dresbach, Winona County, 
Minnesota. U.S. Nat. Mus. Cat. No. 51885a. 
LIncuLeLtta (LINGULEPIS) ACUMINATA MEEKI (Walcott) (p. 550). 
Ficures 2 and 2a. Ventral and dorsal valves from Locality 302b, Middle Cambrian limstone near Crowfoot Ridge 
Yellowstone National Park, Wyoming. U.S. Nat. Mus. Cat. Nos. 35206a and 35206b, respectively. 
Figure 2 represents the type specimen. 
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