PLATE VI. 



Upper Ordovician Ccplialopocla: Machiakmt Limestone. 



Drawings by K. C. Liu 



Fig. 1. Cycloceras? peitoutzense Grabau ................................................................... p. 03 



Fragment of the small end of a shell with rounded annulations. Natural size. 

 Machiakou limestone, Pei-Tou-Tze (near Chao-Kou-Chuang) , Chihli. (Cotype, G. 

 S. Ch. Cat. No. 28). 



Fig. 2. Cycloceras? peitoutzense Grabau .................................................................... p. 63 



Living chamber (without septa) of an immature iudividual, with sharp annulations. 

 Natural size. Machiakou limestone, Pei-Tou-Tze (Kaiping basin), Chihli. (Co- 

 type, G. S. Ch.Cat. No. 29). 



Fig. 3. Cycloceras? peitoutzense Grabau .................................................................... p. 63 



The largest specimen obtained, partly embedded in rock. In the upper part is 

 shown a portion of what was probably the living chamber. The surface here shows 

 very fine concentive stria? (see fig. 4). The lower part, which appears to be part of 

 the same specimen does not preserve the stria?. The position of the two fragments, 

 and the form of the smaller one suggest that the shell was curved. Natural size. 

 Mackiakou limestone, Chao-Kou-Chuang, Chihli. (Cotype, G. S. Ch. Cat. 

 No. 107). 



Fig. 4. Cycloceras? peitoutzense Grabau .................................................................... p. 63 



Enlargement of part of surface of figure. 3, (X 3.) to show the fine concentric 

 stria?. 



Fig. 5. Stereoplasmoceras pseudoscptalum Grabau ...................................................... p. 66 



5a. Longitudinal section of a large specimen, not showing siphuncle, but showing 



pseudosepta and stereoplasmic filling. Natural size. 



5b. Cross section of the same. Natural size. Machiakou limestone, Tangshan, Chihli. 

 (Cotype, G. S. Ch. Cat, No. 58). 



Fig. 6. Stereoplasmoceras pseudoseptatum Grabau ....................................................... p. 66 



6a. Longitudinal section, showing depth of septa, pseudosepta, and filling of stere- 



oplasm. Natural size. 



Ob. Cross-section of same. Natural size. Machiakou limestone, Ning-Yang. Shantung. 

 (Cotype, G. S. Ch. Cat. No. 57). 



Fig. 7. Stereoplasmoceras pseudoscptatnm Grabau ....................................................... p. 66 



A natural section, weathered, showing the septa, pseudosepta and excentric 

 siphuncle. The strongly nummuloidal character is shown in the lower part and the 

 non-Actinoceran type of filling in the upper. Natural size. Machiakou limestone, 

 Chao-Kou-Chuang, Chihli. (Cotype, Survey Expedition Coll., G. S. Ch. Cat, 

 No. 78). 



Fig. 8. Stereoplasmoceras macJtiakouncnse Grabau ...................................................... p. 68 



A natural section in the rock, showing narrowly nummuloidal siphuncle, pseudo- 

 septa and filling of stereoplasm . Natural size. Machiakou limestone, Ma-Chia-Kou, 

 Chihli. (Holotype, IT. C. Tan Coll., G. S. Ch. Cat, No. 15). 



US 



