104 BULLETIN 164, UNITED STATES NATIONAL MUSEUM 



Formation and locality. — Lower Ordovician, Wuting formation: 

 In the black banded limestones near San-tao-kang-tzu, 1.5 miles 

 north of the Pen-hsi-hu colliery, Liao-timg, Manchuria. 



Holotype.—V.S.'^M. No. 83747. 



ORMOCERAS NAGAOI, new species 



Plate 21, Figure 11 ; PiuVte 40, Figube 2 



Description. — The holotype is 68 mm long, enlarging slightly from 

 the base to the top. The cross sections of the conch and the si- 

 phuncle, apparently, are circular, but only the lateral half of the spec- 

 imen remains. The siphuncle is located somewhat ventral of the 

 center of the conch ; 4.7 camerae occupy a length equal to the diameter 

 of the conch. "Where the diameter of the conch is 14.5 mm, the 

 concavity of the septa is 4 mm; the maximum diameter of the si- 

 phuncle here is estimated at 6 mm, and the height of its camerae 

 averages 3 mm. The segments of the siphuncle are rather depressed 

 globular. The septal necks are short, usually 0.7 mm or less in 

 length. The interior of the siphuncle is filled with actinoceroid ma- 

 terials, but the usual endosiphuncular passage 1.5 mm wide and its 

 diverticula into the outer surface of the segments of the siphuncle 

 lack such deposits. The ventral sides of the camerae are almost 

 entirely filled with calcareous material, which become less in the 

 younger part, while the dorsal part is almost empty. Some deposits 

 of the calcareous matrix, however, are found on the anterior surface 

 of the septa, which are thin at the margin but gradually thicken 

 toward the siphuncle and abruptly thin out later, assuming a saucer- 

 like shape before reaching the connecting rings. Living chamber 

 and the surface of the shell unknown. 



The specific name is given in honor of Dr. T. Nagao, a professor 

 at the Hokkaido Imperial University in Japan. 



Comparisons. — This species may be allied to Ornioceras kimurai^ 

 but it is easily distinguished by the larger concavity of the septa and 

 the fewer camerae in a length equal to the diameter of the conch. 



Formation and locality. — Middle Ordovician, Ssuyen formation : 

 A black limestone bowlder believed to have come from a part of 

 Ssuyen formation; collected in river drift at the Niu-hsin-tai col- 

 liery, Liao-tung, Manchuria. 



Holotype.— [J. ^.'^.U. No. 83748. 



ORMOCERAS ORIENTALE, new species 



Plate 21, Figtjbes 1-4 



1927. Actinoccras suampanoidcs Kobayashi (not Grabau), Jap. Journ. Geogr. 

 and Geo!., vol. 5, no. 4, p. 19G, pi. 20, fig. 13 ; pi. 21, figs. 10-12. 



Description. — The holotype is 42 mm long, enlarging laterally 

 from a diameter of 10.5 mm at the base to 12.5 mm at a point 32 mm 



