DESCRIPTION OF PLATE I. 
G lobigerina ? mantoensis Walcott (p. 59). , . 5 : 
1. Exterior view of a bilobed specimen, X 8. From Locality C5, Middle Cambrian, Kiu-lung group, 
southwest of Yen-chuang, Shan-tung. U.S. Nat. Mus., Cat. No. 57613. 
Protospongia chloris Walcott (p. 59). 
2 and 2a. Spicules showing form and lines of separation of inner and outer portions of rays, X 6. From 
Locality C4, Middle Cambrian, Kiu-lung group, southwest of Yen-chuang, Shan-tung. U.S. 
Nat. Mus., Cat. Nos. 57614 and 57615. 
Coscinocyathus elvira Walcott (p. 60). 
3. Exterior view of a small cup, X 8. U.S. Nat. Mus., Cat. No. 57724. 
3a. A fragment of cup greatly enlarged to show poriferous outer surface, X 8. U.S. Nat. Mus., Cat. 
No. 255 
3b. Oblique neha of portion of small cup showing poriferous wall, and cross-sections of walls of cup 
toward apex, X 8. U.S. Nat. Mus., Cat. No. 57726. 
3c. Enlargement of partly abraded surface where it is divided into slightly irregular squares by 
radiating septa and concentric dissepiments. U.S. Nat. Mus., Cat. No. 57727. 
The specimens illustrated by figs. 3, 3a-c are from Locality C75, Middle Cambrian, Ki-chéu formation, 
south of Wu-t’ai-hién, Shan-si. 
Protospongia sp. undt. Walcott (p. 60). 
4. Spicule showing the character of the spicule, X 6. From Locality 35n, Middle Cambrian, Fu-chéu 
series limestone, Liau-tung, Manchuria. U.S. Nat. Mus., Cat. No. 57728. 
Planolites sp. undt. Walcott (p. 61). 
5. View of specimen described. Natural size. From Locality 36f, Middle Cambrian, Fu-chéu series, 
Liau-tung, Manchuria. U.S. Nat. Mus., Cat. No. 57732. 
Micromitra sculptilis (Meek) (p. 61). 
6. Summit and side views of a ventral valve, X 6. U.S. Nat. Mus., Cat. No. 57729. 
6a. Exterior of dorsal valve, X 6. U.S. Nat. Mus., Cat. No. 57730. 
The specimens represented by figs. 6 and 6a are from Localities 85n and 35r, Middle Cambrian, 
Fu-ch6u series in limestone, Liau-tung, Manchuria. 
Micromitra (Paterina) lucina Walcott (p. 62). 
7. Summit, side, and back views of a ventral valve, X 6. U.S. Nat. Mus., Cat. No. 57559. 
7a. Exterior of a dorsal valve, X 6. U.S. Nat. Mus., Cat. No. 57731. 
The specimens represented by figs. 7 and 7a are from Locality 35r, Middle Cambrian, Fu-chéu series 
in limestone, Liau-tung, Manchuria. 
Micromitra (Paterina) labradorica orientalis (Walcott) (p. 62). 
8. Exterior view of type specimen of dorsal valve, X 4. From Locality C9, Middle Cambrian, Kiu-lung 
group, southwest of Yen-chuang, Shan-tung. U.S. Nat. Mus., Cat. No. 52516. 
Micromitra (Iphidella) pannula maladensis (Walcott) (p. 63). 
9 and 9a. Summit view and side outline of a ventral valve, X 6. Locality 835n, Middle Cambrian, 
Fu-chéu series limestone, Liau-tung, Manchuria. U.S. Nat. Mus., Cat. No. 57733. 
Micromitra (Iphidella) pannula ophirensis (Walcott) (p. 63). 
10, 10a, and 10b. Top, side, and back views of a partly exfoliated ventral valve, X 4. Locality 35n, 
Middle Cambrian, Fu-chéu series in limestone, Liau-tung, Manchuria. U. S. Nat. Mus., 
Cat. No. 57735. 
Obolus chinensis (Walcott) (p. 64). 
11. Partly exfoliated, broad form of ventral valve, X 6. U.S. Nat. Mus., Cat. No. 52532a. 
11a. Interior of narrow form of ventral valve, X 6. U.S. Nat. Mus., Cat. No. 525320. 
110. Partly exfoliated dorsal valve, showing visceral area and central muscle scars (kh), X 6. U.S. Nat. 
Mus., Cat. No. 52532d. 
The specimens illustrated by figures 11, 11a—0 are from Locality C 62, Middle Cambrian, Kiu-lung group, 
argillaceous limestone, south of Yen-chuang, Shan-tung. 
11¢. Enlargement to 2 diameters of a portion of a slab of limestone on which several ventral and dorsal 
valves of this species occur. [For further illustration see Walcott, 1912), plate xxxrx, figs. 
7a-b.] Locality 85n, Middle Cambrian, Fu-choéu series in limestone, Liau-tung, Manchuria. 
U.S. Nat. Mus., Cat. No. 57736. 
Obolus obscurus Walcott (p. 66). 
12. Interior of an imperfectly preserved dorsal valve, X 6. U.S. Nat. Mus., Cat. No. 52536a. 
12a. Exterior of an exfoliated, partly restored dorsal valve, X 12. U.S. Nat. Mus., Cat. No. 525360. 
126. Partly exfoliated and broken ventral valve showing concentric and radiating lines on the inner 
layers of the shell, X 4. U.S. Nat. Mus., Cat. No. 52535a. 
12c. Enlargement of the concentric strie of the exterior surface, X 8. U.S.Nat. Mus., Cat. No. 525350. 
12d. Exterior surface of a broken dorsal valve, X 6. U.S. Nat. Mus., Cat. No. 52535¢. 
Figures 12 and 12a represent specimens from Locality C63, Middle Cambrian, Kiu-lung group, south- 
west of Yen-chuang, Shan-tung; and 12b-d, specimens from Locality C75, Middle Cambrian, 
Ki-ch6u formation, south of Wu-t’ai-hién, Shan-si. 
Micromitra (Iphidella) pannula White. 
13. Ventral valve, X 3, showing setz and pedicle, from Locality 835k, Middle Cambrian, Burgess shale 
member of Stephen formation on mountain slope between Mount Field and Mount Wapta, 
north of Field, British Columbia, Canada. U.S. Nat. Mus., Cat. No. 59801. 
This illustration is inserted in order to give a better conception of the shells illustrated by figs. 9 and 1o. 
230 
