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PLATE IV. 



Ordovician C< iiJiulopoda; Luirrr Ordovirian: — PciUiilr.f, Liavijchiashan, and Yclili Lime- 

 stones; i'jipcr Ordovician: — Maehialou Limestone. 



Drawings by Lv. C. Liu (^H^j^) 



Fig. 1. rrulcrocanieroci ras matliicui (Jiabau p. 36 



la. Lateral view of a weathered specimen showing part of the siphuncle, and several 



camera'. Natural size, 

 lb. End view of the same sperimen sliowing aperture of endosiphocone. Natural size. 

 Ic. Section of the same showing form and position of siphuncle. Natui-al size. 



Peilintze limestone, Shih-jMuu-Chai, near Chingwangtao, eastern Chilili. (Cotype, 



Coll. by F. F. :\hithieu, C. S. Ch. Cat. No. 100) . 



Fig. '1. I'rotcrocaiiicrocrrax niatliicni Crabau p. 3*3 



2a. Yivw of a small }ioi tion of the shell embedded in rock, showing ilattened siphuncle 



and camera', natural size. 

 2b. End vJe\v of the same, natural size; 



.V portion of the shell and adjoining part of the sii)huncle enlarged to show the 

 relation of the sipbuncular funnels to the outer shell on tlie ventral side, Peilintze 

 limestone, Shih-Mun-Chai, near Chingwangtao, eastern Chihli. (Cotype, Coll. F. 

 F. Mathieu, G. S. Ch. Cat. No. lUl). 



Proterocanieroceras matliiriii tirabau p. 36 



3a. A free siphuncle in three sections. > Natural size. 



;jb.-3e. End views of the same at points indicated, x -'. Peilintze limestone, Shih- 

 Mun-Chai, near Chingwangtao, eastern Chihli. (_ Cotype, F. F. Mathieu Coll., G. 

 S. Ch. Cat. No. 10-2). 



Fig. 4. Camcroccras stijliforrne Grabau p. 39 



la. The siphuncle of a young or apical portion of a shell, sliowing the rate of tapering 



and oblique annulatiops. Enlarged twice, 

 lb. Enlargement of tlic broken smaller end of the same specimen showing the flat 

 ventral side, the endosiphocoleon, and an older endosheath with open lumens 

 remaining; x I. Liangcliiashan limestone (Lower Ordovician) , Liang-Chia-Shan, 

 Siiih-Mun-Chai, eastern Chihli. (Cotvpe, F. F. Mathieu, G. S. Ch. Cat. 

 No. 10:;) 



(,'u nicrocenis sti/lil'iirmc < irabau p. 39 



A'entral view of an older portion of the siphuncle, showing the ventral saddle 

 fornied by the septa. Natural size. 

 r,h. Ljiper, and .jc. lower ends nf the fragment enlarged x 2. to show the endosiphoco- 

 Iciin. Liangcbiashan limestone, Shih-Alun-Chai, near Chingwangtao eastern Chihli. 

 Lower Ordovician. (Cotyiie, Coll. F. F. Mathieu, G. S. Ch. Cat. No. 101). 



Fig. <i. Cuiiici'iiceras sljilil'iirnic Craljau p. 39 



Ga. Lateral view of a silicified fragment of the siphuncle, of a more mature portion than 



tliat represented by tigs. 1 & o showing portions of the septa adhering x 2. 

 6b. Upper and 6c. lower ends of the fragment, showing the last endosheath, its 

 continuation in the endosiphocoleon and indications of older sheaths x 2. Liang- 

 cliiashan limestone, Liang-Chia-Shan Shih-lMun-Chai, near Chingwangtao, eastern 

 Chilili. (Cotype, Coll. F. F. Mathieu, t!. S. Ch. Cat. No. lUo) . 



Fig. 7 SfLcroccruK ijclihcnKr (ii-abau p, 40 



7a. View of the type sjiccimen as exiwsed on tlic rock surface. Natural size. 



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