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. 

 ia. Transverse section of specimen, associated with specimen represented by fig. ib. U. S. Nat. Mus., 



Cat. No. 578122. 

 ib. Ventral side of a specimen that tapers more rapidly than the specimen represented by fig. i,X 8. 



From Locality C57, Middle Cambrian, Kiu-lung group, north of Sin-t'ai-hien, Shan-tung. 



U. S. Nat. Mus., Cat. No. 578126. 



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 Chon-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 C56, Upper Cam- 



brian, Ch'au-mi-tife 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- 



40. Side view of fragment of chambered portion of shell, X 6. U. S. Nat. Mus., Cat. No. 57820. 

 4^. End view of specimen shown by fig. 40, showing form of transverse section and position and size of 



siphuncle, X 6. 

 6,c. 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 C 56, Upper Cambrian, Ch'au-mi-tien limestone, west 

 of Tsi-nan, Shan-tung. 



Orthotheca delphus Walcott [see figs, i, la-b] (p. 96). 



5. Photograph (X 4) of a fragment of limestone containing specimens of this species. From Locality 



35 r, Middle Cambrian, Fu-ch6u series, Liau-tung, Manchuria. U. S. Nat. Mus., Cat. No. 



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, 230] (p. 97) and Hyolithes cybele Walcott [see plate 5, figs. 

 16, i6a-c] (p. 92). 



7. Photograph (X 4) of fragment of limestone containing specimens of the two species 0. glabra and //. 



cybele, and brachiopods Obolits, Acrothele, and Acrotreta. From Locality 35n, Middle Cam- 

 brian, Fu-ch6u 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. 



240 



