DESCRIPTION OF PLATE 5. 
Syntrophia orthia Walcott (p. 85). 
1. Exterior view of a ventral valve, X 3, from Locality 0 56, Upper Cambrian, Ch’au-mi-tién limestone, 
Pagoda Hill, Tsi-nan, Shan-tung. U.S. Nat. Mus., Cat. No. 52562. 
1a. Exterior view of a ventral valve with a narrower median sulcus than the specimen represented 
by fig. 1, X 3. Specimen from Locality C64, Upper Cambrian, Kiu-lung group, 2.7 miles 
(4.3 km.) southwest of Yen-chuang, Shan-tung. U.S. Nat. Mus., Cat. No. 52563. 
1b. Exterior view and side outline of a dorsal valve, X 3, from Locality C54, Upper Cambrian, Ch’au- 
mi-tién limestone, two-thirds of a mile (1.1 km.) west of Tsi-nan, Shan-tung. U.S. Nat. Mus., 
Cat. No. 52561. 
Scenella ? dilatatus Walcott (p. 87). 
2. Fragmentary specimen, showing what is supposed to be the outer surface of the campanulate border, 
X 3. U.S. Nat. Mus., Cat. No. 57767. 
2a. Interior surface of the campanulate border, showing the base of the elevated central portion, X 3. 
U. S. Nat. Mus., Cat. No. 57768. 
From Locality C70, Middle Cambrian, Ki-chéu limestone, south-southeast of Tung-yii, Shan-si. 
Scenella clotho Walcott (p. 86). 
3 and 3a. Summit view of a specimen from which the apex has been broken, with its matrix (3a), 6. 
From Locality C18, Middle Cambrian, Ch’ang-hia limestone, east of Ch’ang-hia, Shan-tung. 
U.S. Nat. Mus., Cat. No. 57769. 
Scenella sp. undt. Walcott (p. 87). 
4. Summit view of the only specimen in the collection. From Locality C56, Upper Cambrian, Ch’au- 
mi-tién limestone, Pagoda Hill, Tsi-nan, Shan-tung. U.S. Nat. Mus., Cat. No. 57770. 
Matherella circe (Walcott) (p. 88). 
5. View of the outer whorl of the spire of the type specimen, with a side outline, X 6. From Locality 
C56, Upper Cambrian, Ch’au-mi-tién limestone, Pagoda Hill, Tsi-nan, Shan-tung. U. S. 
Nat. Mus., Cat. No. 57771. 
Straparollina sp. undt. Walcott (p. 88). 
6. View of the lower side of the outer whorl of the only specimen in the collection, & 2. From Locality 
C55, Middle Cambrian, Kiu-lung group, south of Tsi-nan, Shan-tung. U.S. Nat. Mus., 
CataNo.57772; 
Helcionella ? clurius (Walcott) (p. 90). 
7. Dorsal and side views of the type specimen described in the text. Natural size. From Locality 
C46, Middle Cambrian, Ch’ang-hia limestone at Ch’au-mi-tien, Shan-tung. U.S. Nat. Mus., 
Cat. No. 57773. 
Helcionella rugosa chinensis (Walcott) (p. 91). 
8. Side view of the type specimen, showing the septum toward the apex, X 2. From Locality C3, 
Lower Cambrian, Man-t’o shale, southwest of Yen-chuang, Shan-tung. U.S. Nat. Mus., 
Cat. No. 57774. 
Pelagiella chronus (Walcott) (p. 88). 
9 (C4) and 9a (C1). View of dorsal side of two specimens, showing slight variation in the position of the 
sharp ridge, X 10. U.S. Nat. Mus., Cat. Nos. 57778 and 57779. 
9b. Side outline of another specimen, X 10. U.S. Nat. Mus., Cat. No. 57780. 
From Localities C4 and C1, Middle Cambrian, Kiu-lung group, in limestone south and southwest of 
Yen-chuang, Shan-tung. 
Pelagiella pagoda (Walcott) (p. 89). 
10. View of inner side of a specimen preserving the exterior shell, X 10. U.S. Nat. Mus., Cat. No: 
57782. 
10a. View of inner side of the cast of a large specimen, X 4. U.S. Nat. Mus., Cat. No. 57783. 
From Locality C56, Upper Cambrian, Ch’au-mi-tién limestone, Pagoda Hill, Tsi-nan, Shan-tung. 
Helcionella ? ? simplex (Walcott) (p. 92). 
11. Summit and side view of the type specimen, X 10. From Locality C70, Middle Cambrian, Ki-chéu 
limestone, south-southwest of Tung-yii, Shan-si. U.S. Nat. Mus., Cat. No. 57777. 
Pelagiella willisi (Walcott) (p. 90). 
12. View of outer side of a specimen preserving the outer and inner whorls, X 10. U.S. Nat. Mus., 
Cat. No. 57784. rab 
13. View of the inner side of a specimen showing a slight depression within the dorsal angle, X ro. 
U. S. Nat. Mus., Cat. No. 57785. 
From Locality C72, Middle Cambrian, Ki-chéu formation, east of Fang-lan-chén, Shan-si. 
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