PLATE XXIII. 83 
OxBo.Lus SEPrALIS (Walcott) (p. 414). 
(Pl. XXXIV, figs. 2, 2a.) 
Fieure 3d. Dorsal valve from Locality 14s, Middle Cambrian Ogygopsis zone on Mount Stephen, British Columbia. 
U.S. Nat. Mus. Cat. No. 24069a. Copied from Walcott [1908c, Pl. I, fig. 2a], where it was figured 
as Obolus mcconnelli. 
OBOLUS MCCONNELLI DECIPIENS Walcott (p. 398). 
Fiaure 4. Compressed ventral valve, the type specimen, from Locality 7v, Upper Cambrian shales 4.25 miles south- 
southeast of Emigrant Peak, Esmeralda County, Nevada. U.S. Nat. Mus. Cat. No. 51586a. 
4a. Compressed ventral valve from Locality 8m, Middle Cambrian limestone 4 miles northeast of Osceola, 
White Pine County, Nevada. U.S. Nat. Mus. Cat. No. 51585a. : 
4b. Ventral valve associated with specimen represented by figure 4a. U.S. Nat. Mus. Cat. No. 51585b. 
OxsoLus FRAGILIS (Walcott) (p. 392). 
Ficure 5. Cast of the interior of a ventral valve, the type specimen, from Locality 1, Middle Cambrian shales on 
Manuels Brook, Conception Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 27317a. 
5a. Dorsal valve associated with the specimen represented by figure 2. U.S. Nat. Mus. Cat. No. 27317b. 
5b. Outline of the dorsal valve, showing area, from Locality 2, Middle Cambrian shale from a higher horizon 
than that represented by figure 5, on Manuels Brook, Conception Bay, Newfoundland. U.S. Nat. 
Mus. Cat. No. 56911a. 
5c. Cast of the interior of a dorsal valve associated with the specimen represented by figure 5. U.S. Nat. 
Mus. Cat. No. 27317c. 
5d. Cast of the interior of a dorsal valve, showing concentric and radiating striz, associated with specimen 
represented by figure 5b. U.S. Nat. Mus. Cat. No. 56911b. 
5e. Broad dorsal valve associated with specimen represented by figure 5. U.S. Nat. Mus. Cat. No. 27317d. 
