DESCRIPTION OF PLATE 3. 
Lingulella manchuriensis Walcott (p. 69). 
1. Summit view and side profile of a ventral valve, X 10. U.S. Nat. Mus., Cat. No. 57560. 
1a. Summit view and side profile of a ventral valve, X 10. From Locality 35q, Middle Cambrian, 
Fu-choéu series, collected in a low bluff on the shore of Tschang-hsing-tau Island, east of 
Niang-niang-kung, Liau-tung, Manchuria. U.S. Nat. Mus., Cat. No. 57750. 
1b. Summit view and side profile of an exfoliated dorsal valve, X 10. U.S.Nat. Mus., Cat. No. 57561. 
1c. Summit view and side profile of partly exfoliated broad form of dorsal valves. U.S. Nat. Mus., 
Cat. No. 57751. 
1d. Summit view and side outline of a dorsal valve, exhibiting the outer surface of the shell, X 10. 
U. S. Nat. Mus., Cat. No. 57752. 
1e. Enlargement to 4 diameters of a number of valves of this species, flattened in a fine arenaceous shale. 
U.S. Nat. Mus., Cat. No. 57753. 
The specimens represented by figs. 1, 1b-e are from Locality 35p, Middle Cambrian, Fu-chéu series, 
calcareous and finely arenaceous shales, Province of Liau-tung, Manchuria. 
Lingulella (Lingulepis) eros (Walcott) (p. 70). 
2. Exterior of a broken ventral valve, X 8. From Locality C7, Middle Cambrian, Kiu-lung group, 
west of Yen-chuang, Shan-tung. U.S. Nat. Mus., Cat. No. 525274. 
2a. Exterior of an associated broken dorsal valve, X 8. U.S. Nat. Mus., Cat. No. 525270. 
Dicellomus parvus Walcott (p. 71). 
3. Exterior of a ventral valve, X 10. U.S. Nat. Mus., Cat. No. 52523¢. 
3a and 30. Interiors of dorsal valves, X 10. U.S. Nat. Mus., Cat. Nos. 52523¢ and 52523). 
3c. Exterior of a dorsal valve, X 10. U.S. Nat. Mus., Cat. No. 52523d. 
3d. Exterior of a young shell, X 10. U.S. Nat. Mus., Cat. No. 52523¢. 
All of the specimens illustrated are from Locality C6, Middle Cambrian, Kiu-lung group, thin platy lime- 
stone, southwest of Yen-chuang, Shan-tung. The specimen represented by fig. 3a is on a piece of 
limestone with Drepanura premesnili Bergeron. 
Obolella asiatica Walcott (p. 72). 
4. Exterior of a ventral valve, X 4. From Locality C32, Lower Cambrian, drift bowlder, Southern 
Shan-si. U.S. Nat. Mus., Cat. No. 52525a. 
4a. Exterior of an associated dorsal valve, X 4. U.S. Nat. Mus., Cat. No. 525250. 
Yorkia ? orientalis Walcott (p. 72). 
5. Summit and side views of a ventral valve, X 8. U.S. Nat. Mus., Cat. No. 52521. 
5a. Diagrammatic sketch of the minutely ornate exterior surface. 
From Locality C71, Middle Cambrian, Ki-ch6éu formation, southwest of Tung-yii, Shan-si. 
Acrothele matthewi eryx Walcott (p. 73). 
6. Summit and side views of a partly exfoliated ventral valve, X 3. From Locality C4, Middle Cambrian. 
Kiu-lung group, limestone nodules southwest of Yen-chuang, Shan-tung. U.S. Nat. Mus., 
Cat. No. 52520. 
6a. Summit view and side outline of a ventral valve, X 8. U.S. Nat. Mus., Cat. No. 57754. 
6b. A large ventral valve compressed in fine arenaceous shale, X 2. U.S. Nat. Mus., Cat. No. 57755. 
6c. A compressed and partly exfoliated ventral valve, showing faint radiating ridges, X 3. U.S. Nat. 
Mus., Cat. No. 57756. 
6d. Enlargement to 6 diameters of the posterior portion of a ventral valve, showing apex and false area, 
X 6. U.S. Nat. Mus., Cat. No. 57757. 
6e. View of a large dorsal valve, X 2. U.S. Nat. Mus., Cat. No. 57758. 
6f. A large dorsal valve compressed in finely arenaceous shale, X 2. U.S. Nat. Mus., Cat. No. 57759. 
6g. An exfoliated ventral valve, showing muscle scars and vascular markings, X 4. U.S. Nat. Mus., 
Cat. No. 57760. 
6h. View of a small, partly exfoliated dorsal valve, showing cast of a portion of a median ridge and the 
pits adjoining it near the beak. U.S. Nat. Mus., Cat. No. 57761. 
The specimens represented by figs. 6a, 6c-e, and 6g-h are from the limestones of Locality 35r, Middle 
Cambrian, Fu-ch6éu series, Province of Liau-tung, Manchuria. 
The specimens represented by figs. 6b and 6f are from finely arenaceous buff-colored shale, Localities 
36e and 86g, Middle Cambrian, Fu-chéu series, Province of Liau-tung, Manchuria. 
Acrothele ? minuta Walcott (p. 74). 
7. Exterior of a dorsal valve, X 15. From Locality C6, Middle Cambrian, Kiu-lung group, thin platy 
limestone, southwest of Yen-chuang, Shan-tung. U.S. Nat. Mus., Cat. No. 52519. 
Acrothele rara Walcott (p. 74). 
8. Interior of a ventral valve, X 6. From Locality C57, Middle Cambrian, Kiu-lung group, limestone 
nodules, north of Sin-t’ai-hién, Shan-tung. U.S. Nat. Mus., Cat. No. 52518a. 
8a. Interior of an associated dorsal valve, X 6. U.S. Nat. Mus., Cat. No. 525180. 
Acrotreta lisani Walcott (p. 75). 
9, 9a, and 9b. Summit, back, and side views of ventral valve, X15. From Locality 022, Middle Cam- 
brian, Ch’ang-hia limestone, at Ch’ang-hia, Shan-tung. U.S. Nat. Mus., Cat. No. 525054. 
gc. Exterior of an associated dorsal valve, X 15. U.S. Nat. Mus., Cat. No. 52505). 
Acrotreta venia Walcott (p. 77). 
10. Summit, side, and back views of a ventral valve, X 8. U.S. Nat. Mus., Cat. No. 57763. 
rod. pate of a tae valve showing median ridge and posterior muscle-scars. U.S. Nat. Mus., Cat. 
0. 57595. 
10), Exterior of very perfect dorsal valve, X 8. U.S, Nat. Mus., Cat. No. 57564. 
The specimens represented by figs. 10, 10a—b are from the shaly limestones of Locality 35q, Middle 
Cambrian, Fu-chéu series in compact shaly limestone about 120 feet (36.5 m.) above Locality 35p 
from which Lingulella manchuriensis comes, Province of Liau-tung, Manchuria. 
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