FORMATION'S AND FOSSILS OF SOUTH MANCHTJEIA 77 



camerae in a length equal to the diameter of the conch is nine. 

 Where the diameter of specimen is 19 mm and where the septa are 

 2 mm apart, one of the siphuncle segments has a maximum diameter 

 of 3 mm at mid height, constricting to 1.2 mm at its passage through 

 the septum. The resultant form of the siphuncle segments is globu- 

 lar. Septal necks very short; envelope on the interior of the 

 siphuncle by lunate calcareous deposits, leaving rather a large endo- 

 siphuncular passage. The septa are thickened rather slightly with 

 the deposition of calcareous matrix at both the upper and lower sides. 



Living chamber and surface of the conch unknown. 



The specific name is given in honor of Y. Inai, a prominent pale- 

 ontologist in Manchuria. 



C omparisons — This species is closely allied to Sactoceras manitou- 

 linense Foerste from the clay cliffs at Meaford, Canada, but it is dis- 

 tinguished by the much more excentric siphuncle and its more de- 

 pressed segments. Moreover, in the Manchurian specimen, nine 

 camerae occur in a length equal to the diameter of the conch, while in 

 8. manitoulmense this number is six or seven. 



Formation cmd locality. — ^Middle Ordovician, Ssuyen formation: 

 Lower fossil horizon of the black banded limestone at Tou-f ang-kou, 

 2.5 miles northwest of Pen-hsi-hu, Liao-tung, Manchuria. 



Holotype.—V.S.'^M. No. 83700. 



SACTOCERAS species nndetermined 



Plate 13, Figure 7 



A fragmental specimen (U.S.lSr.M. No. 83701) 29 mm long has a 

 very low apical angle. Five camerae occur in a space equal to the 

 diameter of the conch. The cross section of the conch apparently 

 is depressed. Where the diameter of the conch is 8.5 mm, the con- 

 cavity of the septa is 1.2 mm ; the maximum diameter of the siphuncle 

 here is estimated at 2.8 mm, and height of its camerae averages 2 mm. 

 The interior of the siphuncle is densely filled with calcareous matrix. 

 The septa are moderately thickened with the deposition of calcareous 

 matrix on the anterior side of each septum. 



Formation and locality. — Middle Ordovician, Ssuyen formation: 

 Lower fossil horizon of the black banded limestone, near the Pen- 

 hsi-hu colliery, Liao-tung, Manchuria. 



SACTOCERAS species undetermined 



Plate 14, Figure 11 



A fragmental specimen (U.S.N.M. No. 83702) is 53 mm long, 18.6 

 mm in diameter near the base, and estimated to have been 25 mm in 

 diameter at a point 32 mm farther up, thus indicating an apical 

 101621—32 6 



