68 BULLETIN 164, UNITED STATES NATIONAL MUSEUM 



The specific name is given in honor of S. Toyama, a prominent 

 Manchurian paleontologist. 



Comparisons. — This species may be related to Tofangoceras pau- 

 ciannulatum Kobayashi, but differs from it in having rather longer 

 camerae and slighter annulation of the surface of the shell. 



Even though my specimens have characteristics of Tofangoceras 

 in possessing surface annulations and a slightly nummuloidal 

 siphuncle, these characters are very poorly developed as compared 

 with that of the genotype of Tofangoceras. On the contrary, the 

 generic characters of my specimens are comparable rather with 

 Orthoceras in showing straight and comparatively smooth longi- 

 cones with simple septae and sutures. Therefore at present I place 

 this species in Orthoceras. If in my future field work, however, I 

 shall have the good fortune to find a whole specimen that is not 

 embedded in the rock matrix, I can then examine the surface an- 

 nulation in more detail, and it may happen that its generic reference 

 will have to be changed. 



Formation and localities. — Middle Ordovician, Ssuyen formation : 

 A grayish black limestone bowlder believed to have come from the 

 Ssuyen formation in river drift at the Niu-hsin-tai colliery; also in 

 drift near the Pen-hsi-hu colliery, Liao-tung, Manchuria. 



Holotype and paratype.—V.^.'^.'M. Nos. 83685 and 83686. 



ORTHOCERAS species nndetermined 



Plate 13, Figures 8, 9 



Specimen (U.S.N.M. No. 83687), 46 mm long, 23 mm in diameter 

 at its top, cross section circular, rate of enlargement very small. 

 The siphuncle is located in a central position. The average length 

 of the camerae is 4.5 mm. Concavity of septa about 4 mm. Diam- 

 eter of siphuncle 2.5 mm at mid height, diminishing slightly at the 

 septal necks. The latter are about 0.7 mm long. The surface of 

 the shell is smooth; living chamber unknown. 



Formation and locality. — Middle Ordovician, Ssuyen formation: 

 A grayish black limestone bowlder supposed to belong to the Ssuyen 

 formation, in river drift at the Niu-hsin-tai colliery, Liao-tung, 

 Manchuria. 



Genus CYCLOCERAS McCoy, 1844 



CYCLOCERAS (?) MANCHURIENSE, new species 



Plate 13, Figures 10-12 ; Plate 14, Figures 8, 9, 12 ; Plate 17, Figuee 7 



Description. — The holotype specimen (pi. 13, figs. 10-12) is 55.5 

 mm long, enlarging from a diameter of 14.5 mm at the base to 18.5 

 mm at the top, the apical angle being rather small. The cross sec- 

 tions of the conch and siphuncle are circular. Four and a half 



