DESCRIPTION OF PLATE 6. 
Orthotheca delphus Walcott [see figs. 5, 6] (p. 96). 
1. View looking down on rounded angle formed by union of dorsal and ventral faces, X 4. From 
Locality C4, Middle Cambrian, Kiu-lung group, southwest of Yen-chuang, Shan-tung. U.S. 
Nat. Mus., Cat. No. 57811. 
1a. Transverse section of specimen, associated with specimen represented byfig.1b. U.S. Nat. Mus., 
Cat. No. 57812¢. 
1b. Ventral side of a specimen that tapers more rapidly than the specimen represented by fig. 1, X 8. 
From Locality C57, Middle Cambrian, Kiu-lung group, north of Sin-t’ai-hien, Shan-tung. 
U. S. Nat. Mus., Cat. No. 57812). 
Orthotheca doris Walcott (p. 97). 
2. Side view and outline of transverse section of type specimen, X 4. From Locality C32, Middle 
Cambrian, Ki-sin-ling limestone, south of Chén-p’ing-hien, Southern Shan-si. U.S. Nat. 
Mus., Cat. No. 57813. 
Orthotheca sp. undt. Walcott (p. 98). 
3. Dorsal view and outline of transverse section of fragment, X 8. From Locality 056, Upper Cam- 
brian, Ch’au-mi-tién limestone, west of Tsi-nan, Shan-tung. U.S. Nat. Mus., Cat. No. 
57814. 
Cyrtoceras cambria Walcott (p. 98). 
4. Side view of specimen preserving chamber of habitation and eight septa, X 4. U.S. Nat. Mus., 
Cat. No. 57819. 
4a. Side view of fragment of chambered portion of shell, X 6. U.S. Nat. Mus., Cat. No. 57820. 
4b. End view of specimen shown by fig. 4a, showing form of transverse section and position and size of 
siphuncle, X 6. 
4c. Side view of fragment of chambered portion of shell, showing curvature of septa, X 6. U.S. Nat. 
Mus., Cat. No. 57821. 
All of the specimens illustrated are from Locality C56, Upper Cambrian, Ch’au-mi-tién limestone, west 
of Tsi-nan, Shan-tung. 
Orthotheca delphus Walcott [see figs. 1, 1a—b] (p. 96). 
5. Photograph (x 4) of a fragment of limestone containing specimens of this species. From Locality 
35r, Middle Cambrian, Fu-chéu series, Liau-tung, Manchuria. U.S. Nat. Mus., Cat. No. 
57815. 
6. Photograph (X 4) of type specimen of species. From Locality C4, Middle Cambrian, Kiu-lung 
group, southwest of Yen-chuang, Shan-tung. U.S. Nat. Mus., Cat. No. 57816. 
Orthotheca glabra Walcott [see plate 5, figs. 23, 23a] (p. 97) and Hyolithes cybele Walcott [see plate 5, figs. 
16, 16a—c] (p. 92). 
7. Photograph (X 4) of fragment of limestone containing specimens of the two species O. glabra and H. 
cybele, and brachiopods Obolus, Acrothele, and Acrotreta. From Locality 35n, Middle Cam- 
brian, Fu-chéu series, Liau-tung, Manchuria. U.S. Nat. Mus., Cat. Nos. 57807 and 57808. 
Hyolithes carinatus Matthew. 
8. Ventral view of a specimen (X 2) with the operculum and the fin or arm supports. From Locality 
35k, 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. 57625. 
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