FORMATIONS AND FOSSILS OF SOUTH MANCHURIA 89 



These rings are in contact with the septa both above and below for 

 a radial width of 1.5 nun. The siphuncle is filled with typical 

 actinoceroid deposits of calcareous material, leaving the rather 

 large central endosiphuncular passage and its diverticula into the 

 outer margin of the connecting rings. The septa are thickened 

 irregularly with the deposition of calcareous matrix on both their 

 upper and lower sides; this calcareous material almost entirely fills 

 in the camerae of the one side and of the older part. Living chamber 

 and surface of the shell unknown. 



The specific name is given in honor of Doctor Kido, former 

 director of the geological survey of the South Manchuria Rail- 

 way Co. 



Comparisons. — This species may be compared to Armenoceras 

 manchurense (Kobayashi), but differs from it in having a smaller 

 apical angle, a larger septal distance, and an almost circular shell. 



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

 A black limestone bowlder believed to have come from the Ssuyen 

 formation, in river drift near the Pen-hsi-hu colliery, Liao-tung, 

 Manchuria. 



Holotype.—TJ.S.'^.M. No. 83719. 



ARMENOCERAS TEICHERTI, new species 



Plate 19, Figure 1; Plate 40, Figure 6 



Description. — The holotype specimen is 69 mm long, enlarging 

 from a lateral diameter of 26 mm near its base to 33.5 mm at a 

 point 38 mm farther up, indicating an apical angle of about 7°. It 

 is estimated that about seven camerae occupied a length equal to the 

 lateral diameter of the conch near the base. The cross sections of 

 the conch and the siphuncle are apparently circular, but only the 

 ventral half of the specimen remains, the dorsal half having weath- 

 ered away. The concavity of the septa is about 6.5 mm. The dis- 

 tance of the siphuncle from the ventral wall of the conch is 4 mm. 

 The diameter of the siphuncle is 10.2 mm ; at a point where its lateral 

 diameter is 10.5 mm, that of the passage of the siphuncle through 

 the septum is 5 mm. Between the connecting rings this septum is 

 horizontal and its inner margin curves slightly downward ; the inner 

 margin extends about 2.5 mm inward from the vertical projection 

 of the outer margin of the septal rings. These rings are in contact 

 with the septa both above and below for a radial width of 2 mm. 

 The interior of the siphuncle is filled with typical actinoceroid cal- 

 careous materials, but the endosiphunclar passage and its diverticula 

 into the outer margin of the connecting rings lack such deposits. 

 The septa are thickened on both upper and lower marginal portions 

 by nearly equal quantities of calcareous material, which leaves nar- 

 row spaces in the middle of each camera. 



