PLATE VIII. 31 
OsoLus NAMOUNA Walcott—Continued. 
Figure 2a. Cast of the interior of a dorsal valve associated on the same hand specimen with the specimen represented 
by figure 2. The remarkable feature of this specimen is the continuation of the lines of growth of the 
area far forward on the shell. U.S. Nat. Mus. Cat. No. 27304b. 
OBOLUS MATINALIS (Hall)? Walcott (p. 402). 
Figures 3 and 3a. Ventral and dorsal valves of partly exfoliated shells from Locality €54, Upper Cambrian Chau- 
mitien limestone, two-thirds mile west of Tsinan, Shantung, China. U.S. Nat. Mus. Cat. Nos. 
52533a and 52533b, respectively. 
