(i) 44 



Palseontologia Sinica 



Scr B. 



In the specimen from which these sections are taken, the annulations of the 

 shell of the siphuncle are finer/there being 5 in the space of 10 mm. This specimen is 

 recorded as from the lower horizon, the Peilintze limestone, whereas the others occur in 

 the upper or Liangchiashan limestone of the Shih-Mun-Chai district. The specimen in 

 question may represent a distinct species. 



HORIZONS AND LOCALITY: Two specimens of this species were obtained by Dr. F. 

 F. Mathieu from the Liangchiashan limestone at Liang-Chia-Shan, Shih-Mun-Chai near 

 Chingwangtao, eastern Chihli province. Another specimen with finer annulations and 

 siphuncle less flattened ventrally, was obtained from the Chihlioceras or Peilintze limestone 

 of the same region (this may possibly be a case of mislabelling). The former horizon is 

 the upper part of the Lower Ordovician. 



Family CHIHLIOCERATID^E Grabau (fam. nov.) 



Genus CHIHLIOCERAS Grabau (gen. nov.) 



Text Figures 2-16 



Breviconic orthoceracones with large and stout siphuncle, which is surrounded by 

 a definite wall or siphuncular shell; with rounded apical end, the center of which is 

 marked by a mammillary elevation with a circular scar, representing the beginning of the 

 endosiphuncle. Siphuncle filled with endosheaths and organically deposited mineral 

 matter as in Piloceras. Endosheaths flattened ventrally, at least in the adult. In the final 

 one, this flat face is produced anteriorly in the form of a blade-like prolongation, which is 



