PLATE IX. 

 Cephalopoda from the Early Upper Ordovician: Machiakou Liinestone. 



Drawings by K. C. Liu (.fij^fefe) 



Fig, 1. Actinoceras suanpanoides Grabau p. 84 



la. Lateral view of a characteristic specimen, showing rate of tapering and distance of 



septa. Natural size. 

 Ib. End view of same. The right side is slightly crushed. Natural size. Machiakou 



limestone, Wfin-Nan, Mon-Yin-Hsien Shantung, V. K. Ting coll. (Cotype, G. S. 



Oh. Cat. No. 111). 



Fig. 2. Actinoceras nanum Grabau p. 87 



A natural section, showing the very slight amount of stereoplasm. Natural size. 

 Machiakou limestone, Tangshan, Chihli. (Paratype, Survey Expedition coll. G. S. 

 Ch. Cat. No. 73) . 



Ftg. 3. Actinoceras submarginale Grabau , p. 86 



A weathered fragment showing the large submarginal siphuncle, and the septa and 

 nearly empty camera. A small part of the shell is preserved in the upper left hand 

 area. Natural size. Machiakou limestone, Tangshan, Chihli. (Cotype, G. S. Ch. 

 Cat. No. 56) . 



Fig. 4. Actinoceras riehthofeni Freeh , p. 7o 



A natural weathered section, showing the forward deflection of the lateral diver- 

 ticula of the endosiphuncle. Natural size. (See text figure 19 p. 79). Machiakou 

 limestone, Lincheng, Shantung, (F. F. Mathieu coll., G. S. Ch. Cat. No. 67). 



Fig, 5. Actinoceras riclitliofeni Freeh p. ""> 



Section of a part of a shell in which the filling of the camera) has been unusually 

 extensive. Natural size. Machiakou limestone, Huo-Luh-Hsien, Chihli. (G. S. 

 Ch. Cat. No. 64). 



Fig. 6. Actinoceras riehthofeni Freeh p. 75 



Section showing part of endosiphuncle, and the moderate amount of filling 

 characteristic of the camera. Natural size. Machiakou limestone, Chihli (?). 

 (Coll. V. K. Ting, G. S. Ch. Cat. No. 52). 



Fig. 7. Actinoceras riehthofeni Freeh ,..p. 7-"> 



7a. Lateral view of a characteristic internal septate mold, showing rate of lateral 



tapering and flexuous character of suture. Natural size. 

 7b. Side view of the same specimen showing the compressed form. On the worn part 



the deep concavity of the septa is indicated. Natural size. 

 7c. View of the polished upper end of the same specimen, showing the oval form of the 



shell and the corresponding oval form and centran position of the siphuncle. 



Natural size. 

 7d. Median longitudinal section of the same specimen, showing the deep concavity of 



the septa, the character of the nummuli with the median endosiphuncle, and the 



lateral diverticula opening in pores on the outer surface of the nummuli. 



Natural size. 

 7e. Surface of the opposite half of the same specimen, separated from 7d by about 1 mm. 



Machiakou limestone, \Vn-Nan, Mon-Yin-Hsien Shantung. V. K. Ting coll. 



(Geol. Survey Ch. Cat. No. 107). 



Fig. 8. Actinoceras riclitliofeni Freeh p. 75 



End view of a fragment of an earlier part of the shell than that shown in fig. 7. 



126 



