PLATE IV. 19 
Micromitra (IPHIDELLA) PANNULA MALADENSIS (Walcott)—Continued. 
Figures 2a/ and 2a’. Side and back views of specimen represented by figure 2a, illustrating the area and pseudodel- 
tidium. 
2b, 2b’, and 2b’. Apical, back, and side views of an elevated ventral valve from Locality 6g, Middle Cam- 
brian limestone, Chapple Arm, Trinity Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 6406e. 4690 
2e. Apical view of an elevated, laterally compressed ventral valve associated with the valve represented by 
figure 2b. U.S. Nat. Mus. Cat. No. 51469b. 
2d and 2e. Exterior of two dorsal valves from Locality 5b, Middle Cambrian limestone, 2 miles southeast of 
Malade, Idaho, with the same type of surface as the specimen represented by figure 2. U.S. Nat. 
Mus. Cat. Nos. 51468¢ and 51468d, respectively. Figure 2e represents the type specimen. 
2f. Partly exfoliated, transverse dorsal valve from locality 6g, Middle Cambrian limestone, Chapple Arm, 
Trinity Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 51469c. 
2¢. Enlargement of a portion of the surface near the center of a ventral valve from Locality 5b, Middle Cam- 
brian limestone, 2 miles southeast of Malade, Idaho, that has (on its frontal portion) a surface like 
that represented by figure 4c of the variety ophirensis. U.S. Nat. Mus. Cat. No. 51468e. 
Mrcromitra ([purpELtaA) PANNULA (White) (p. 361). 
[Text fig. 32, p. 362, and Pl. IV, figs. 1, 1a-t.] 
9 
Ficure 3. Posterior portion of a ventral valve having a very fine surface of the type represented by figure 1q. 
3a and 3a’. Apical and side views of a ventral valve associated with the specimen represented by figure 3. 
The specimens represented are both from Locality 14, Middle Cambrian limestone, 7 miles southwest of Rome, 
Ployd County, Georgia. U.S. Nat. Mus. Cat. Nos. 51444a and 51444b, respectively. 
Mrcromitra ([PHIDELLA) PANNULA OPHIRENSIS (Walcott) (p. 365). 
Fiaures 4and 4’. Apical and side views ofa ventral valve. U.S. Nat. Mus. Cat. No. 51464a. 
da, 4a’, and 4a’’. Apical, back, and side views of a ventral valve, the type specimen, in which the beak 
slightly overhangs the posterior margin. U.S. Nat. Mus. Cat. No. 51464b. (See fig. 4c.) 
4b. Exterior of a dorsal valve with very fine, undulating, concentric strie. U.S. Nat. Mus. Cat. No. 51464c. 
4c. Enlargement of a portion of the specimen represented by figure 4a, to illustrate irregular and inoscu- 
lating strie. U.S. Nat. Mus. Cat. No. 51464b. 
4d and 4d’. Top and back views of a transverse dorsal valve. U.S. Nat. Mus. Cat. No. 51464d. 
4e. Partly exfoliated dorsal valve, showing the cast of a median septum and the position of the central 
muscle scars. U.S. Nat. Mus. Cat. No. 51464e. 
4f. A small, convex dorsal valve. U.S. Nat. Mus. Cat. No.51464f. 
The specimens represented are all from Locality 3e, Middle Cambrian limestone, Oquirrh Range, near Ophir, Utah. 
