88 



of the foci of the ellipse formed by the calicular border. From 

 a short elliptical base the corallum is abruptly expanded to 



the calicular border. 



The length of a specimen is about three-tenths of an inch; 

 shorter diameter of the calyx about four- tenths of an inch, and 

 longer diameter of the calyx about six-tenths of an inch. Onr 

 specimens are silicifled and do not show any epitheca, dissepi- 

 ments, tabula? or columella. 



Found in the Silicifled Subcarbonif erous beds of Lincoln county, 

 Tennessee, which we suppose are of the age of the Keokuk 

 Group, and now in the collection of Wm. F. E. Gurley. 



CLASS, CEPHALOPODA. 

 ORDER, NAUTILOIDEA. 

 Family CYRTOCERATID^E. 



CYRTOCERAS KANSASENSE, n. Sp. 



Plale F, Fig. 5, ventral view; Fig. 6, lateral view; Fig. 7, posi- 

 tion of the siphuncle and convexity of the septa 

 at the fifth air chamber that is preserved, 

 in the specimen illustrated. 



Our specimen is not complete and shows the siphuncle and 

 convexity of the septa at the small end; and has been broken 

 at the fifth septa, so that it may be examined in two places, 

 and figure 7 is taken from a view at the fifth septa. 



The shell rapidly expands, is gently curved, and slightly de- 

 pressed from a true circle, in tranverse section, on the ventral 

 side. The outer shell is preserved forward of the fifth septa, 

 so that only five air chambers can be seen, but the end of the 

 siphuncle indicates there are air chambers forward of that 

 point. The siphuncle is small and near the vental side, the 

 expansion within the air chambers is not disclosed. The con- 

 vexity of the septa is rather more than the length of an air 

 chamber. The septa are distant about one-fifth the diameter 

 of the shell. The outer shell is transversely furrowed. On 

 the ventral side the spaces between the furrows are flattened 

 and wider than the furrows. On the dorsal side the furrows 

 and ridges are subequal. The body chamber is not completely 

 preserved, and the aperture, therefore, is unknown. 



