IV I. Grabau Ordovician Fossils from North China (i) 41 



HORIZON AND LOCALITY: In the lower Yehli limestone of Lower Ordovician age, 

 at Yeh-li, northern rim of Kaiping coal basin. (Y. C. Sun coll.). 



Suecoceras attenuatum Grabau (sp. nov.) 



Plate IV, Figs. 8, 9. 



Like the preceding, this is known only from the siphuncle, which clearly shows 

 it to be a more slender form, and one which never reaches the siphuncular diameter of 

 the preceding species. 



The siphuncle (in fig. 8) gradually increases in diameter from the initial point, 

 reaching its maximum of 9 mm. at a point distant about 20 mm. from the apex. After 

 that it decreases again, until at the uppermost preserved end, it is 7.5 mm., this being 

 about 40 mm. from the apex. In another specimen, the greatest diameter is 9.3 mm. at 

 a point about 25 mm. from the apex, narrowing subsequently to 8.9 mm. 



In one specimen, apparently of this species, the diameter of the siphuncle is 9.8 

 mm. at the upper end, this being the aperture of the endosiphocone or uppermost One of 

 the conical fillings (endosiphosheaths) of the siphuncle (see Plate IV fig. 9). The 

 position of the endosiphosheaths in the siphuncle seems to be oblique, their axis not 







coinciding with the median line of the siphuncle as a whole. 



HORIZON AND LOCALITY : In the lower beds of the Yehli limestone near Yeh-li 

 northern border of the Kaiping coal field, Chihli. (Y. C. Sun coll. ). 





Genus VAGINOCERAS Hyatt 

 Vaginoceras tsinanense Grabau (sp. nov.) 



Plate IV, Figs. lOa, b. 



Represented at present only by the siphuncle, which however has certain very 

 definite characters from which some of the other characters of the shell can be deduced. 



The form of the siphuncle is sub-cylindrical, increasing from 9.6 mm. at the 

 lower preserved end, to 10.8 mm. at the upper, the distance being 40 mm. This gives a 

 rate of tapering of 1 mm. in a length of 33 1/3 mm. 



