PLATE XVIII. 65 
LINGULELLA OWENI (Walcott) (p. 523). 
Ficure 5. Ventral valve showing the exterior surface of the shell, from Locality 86, Upper Cambrian sandstone at 
Gibraltar Bluff, Lodi, Wisconsin. U.S. Nat. Mus. Cat. No. 25330a. 
5a. Enlargement of the area of a cast of a flattened ventral valve in which all traces of a flexure line have been 
lost. Locality 85s, Upper Cambrian sandstone at Prairie du Sac, Wisconsin. U.S. Nat. Mus. Cat. 
No. 27385a. - 
5b. Cast of the interior of a dorsal valve, the type specimen, associated with the specimen represented by 
figure 5. U.S. Nat. Mus. Cat. No. 25330b. 
5c. A smaller and less elongate dorsal valve than that represented by figure 5b, but from the same locality. 
U.S. Nat. Mus. Cat. No. 25330c. 
5d and 5e. Casts of small ventral valves from Locality 78c, Upper Cambrian, sandstone at Osceola, Wis- 
consin. U.S. Nat. Mus. Cat. Nos. 27329a and 27329b, respectively. 
5f. Cast of a dorsal valve from same locality as specimens represented by figures 5d and 5e. U.S. Nat. Mus. 
Cat. No. 27329c. 
OxBoLus piscoipEUs (Hall and Whitfield) (p. 389). 
Figure 6. Exterior ofa partly exfoliated ventral valve. U.S. Nat. Mus. Cat. No. 24555a. 
6a. Dorsal valve, partly exfoliated. U.S. Nat. Mus. Cat. No. 24555b. 
6b and 6c. Probably ventral valves, but it is difficult to determine owing to the rounding of the posterior 
portion of the valve. U.S. Nat. Mus. Cat. Nos. 24555e and 24555d, respectively. Figure 6c is drawn 
from the type specimen figured by Hall and Whitfield [1877, Pl. I, fig. 2]. The specimen repre- 
sented by their figure 1 is not redrawn in this monograph. 
The specimens represented by figures 6, 6a-c are all from Locality 313j, Upper Cambrian limestone in the Eureka 
district, Nevada. 
Figure 6d. Partly exfoliated dorsal valve, showing outline of visceral area, from Locality 62, Upper Cambrian 
Dunderberg shale, north of Adams Hill, Eureka district, Nevada. U.S. Nat. Mus. Cat. No. 51547a. 
62667°—vot 51, pr 2—12 5 : 
