PLATE VIII. 



Upper Ordovician Cephalopoda: MachiaJcou Limestone. 



Drawings by K. C. Liu 



Fig, 1. Actinoceras coulingi Grabau p. 82 



A natural section upon the rock surface, somewhat weathered, and showing the 

 siphuncle, irregular septa, and filling of camera by stereoplasm. Natural size. 

 Machiakou limestone, Hsi-Hsien, Honan. (Cotype, A. C. Taun coll., G. S. Ch. 

 Cat, No. 4). 



Fig. 2. Actinoceras coulingi Grabau p. 82 



Polished section of a characteristic specimen, showing the siphuncle and nature and 

 extent of filling of camera?. Natural size. Machiakou limestone, Ma-Chia-Kou, 

 Chihli. (Cotype, H. C. T'an coll. G. S. Ch. Cat. No. 27). 



Fig. 3. Actinoceras suanpanoides Grabau ;.p. 84 



3a. Somewhat oblique polished section showing depth of camera and their filling, and, 



in the lower part, the siphuncle. The rate of tapering appears abnormally great 



owing to the oblique direction of the section. Natural size. 

 3b. Transverse section of upper end. Machiakou limestone, Tai-An, Shantung. 



(Cotype, G. S. Ch. Cat. No. 53). 



Fig. 4. Actinnceras suapanoides_ Grabau p. N-| 



4a. Polished section, showing the characteristic siphuncle, rate of tapering of shell, and 



filling of camenc. 

 4b. Transverse section of same showing excentric position of siphuncle. Machiakou 



limestone, Shantung. (Cotype, G. S. Ch. Cat, No. 54 j. (See further plate IX). 



Fig. 5. Actinoceras submarginale Grabau p. 86 



5a, Polished section through the siphuncle showing distant septa with camerae largely 



filled by stereoplasm. Also part of the endosiphuncle. Natural size. 

 5b. Transverse section of a part laterally displaced by a small fault, showing size and 

 submarginal position of siphuncle. Natural size. Machiakou limestone, Tangshan, 

 Chihli. (Cotype, G. S. Ch. Cat, No. 55). (See also plate IX). 



Fig. 6. Actinoceras curvatum Grabau p. 88 



A weathered specimen on rock showing curved form, septa with partial filling of 

 camera, and siphuncle. Natural size. Machuikou limestone, Lincheng, Shantung. 

 (Holotyye, F. F. Mathieu coll., G. S. Ch. Cat. No. 77) 



Fig. 7. Cyrtactinoceras frechi Grabau p. 89 



A weathered fragment near the apical end, showing siphuncle and septa, the camera 

 scarcely obstructed by stereoplasm. The slight curvature scarcely appears in this 

 view. Natural size. Machiakou limestone, Tangshan. Chihli. (Cotype, T. C. 

 Wang coll. G. S. Ch. Cat. No. 2). 



Fig. 8. Ci/rtactinoceras frecli i Grabau P- 89 



A small fragment near the apical end, showing sutures. Enlarged X 2. Machiakou 

 limestone. Chao-Kou-Chuang, Chihli. (Cotype, G. S. Ch. Cat. No. 88). 



Fig. 9. Cyrtactinoceras frechi Grabau P- >c 



9a. An apical portion somewhat weathered. Natural size. 



9b. Section of same, showing excentric siphuncle. Natural size. Machiakou limestone, 

 Shantung. (Cotype, G. S. Ch. Cat. No. GG). 



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