76 BULLETIN 16 4, UNITED STATES NATIONAL MUSEUM 



The smaller apical angle, lower concavity of the septa, and smaller 

 ratio between the diameter of the siphuncle and that of the conch 

 serve to differentiate this species from others found in the Ordovi- 

 cian. 



Formation and locality. — Middle Ordovician, Ssuyen formation: 

 Lower fossil horizon of the black banded limestone, 1 mile east of 

 the Niu-hsin-tai colliery, Liao-tung, Manchuria. 



Eolotype.—V.^.'^M. No. 83698. 



SACTOCERAS LIAOTUNGENSE, new species 



Plate 14, Figure 10 



Description. — The holotype is 33.5 mm long, enlarging from 7.5 

 mm at the base to 15 mm at the top, the apical angle being 9°. The 

 cross sections of the conch and siphuncle apparently were circular, 

 but only the lateral half of the conch remains. The siphuncle is 

 located somewhat ventrally. Five camerae occupy a length equal 

 to the diameter of the conch. Where the diameter of the specimen 

 is 13.5 mm and where the septa are 3 mm apart, one of the segments 

 of the siphuncle has a maximum diameter of 2.5 mm at mid height, 

 constricting to 1.2 mm at its passage through the septum. The re- 

 sultant form of segments of the siphuncle is almost globular. The 

 concavity of the septa averages 3 mm. The interior of the siphuncle 

 is moderately filled with calcareous matrix, and that of the camerae 

 is almost entirely filled with the same deposition, leaving a diagonal 

 narrow space at its center. 



Comparisons. — The comparatively small conch and rather large 

 apical angle serve to differentiate this species from others found in 

 the Ordovician beds in the Orient. Moreover, I am not acquainted 

 with any American or European forms with which this species is 

 likely to be confounded. 



Formation and locality. — Middle Ordovician, Ssuyen formation: 

 Lower fossil horizon of the black banded limestones, on the Fu-chin- 

 kou ridge, 2.5 miles southwest of Miyanohara station, Liao-tung, 

 Manchuria. * 



Holotype.— v. ^.'^.'M. No. 83G99. 



SACTOCERAS INAII, new species 



Plate 14, Figure 1 



Description. — The holotype is 47 mm long, 17.5 mm in diameter at 

 the base, and 19.5 mm near the top, the apical angle being very small. 

 The cross section of the conch, apparently, was laterally^ depressed, 

 but the comparatively large part of the dorsal side has weathered 

 away. The location of the siphuncle is very excentric, its distance 

 from the ventral wall of the conch being 2.5 mm. The number of 



