88 



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

 a sl.crt 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. Our 

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

 ments, tabulae or columella. 



Found in the Silicified Subcarboniferous beds of Lincoln county. 

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

 Group, and now in the collection of Wm. F. E. Gux'ley. 



CLASS, CEPHALOPODA. 



ORDER, NAUTILOIDEA. 



Family CYRTOCERATID^. 



CYHTOCERAS KANSASENSE, n. Sp. 



Plate V, Fi(]. 5, iwiitral i^ieiv; Fig. 0, lateral view; Fig. 7, posi- 

 tion of the siphuncle and convexity of the sepia 

 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 rajjidly expands, is gently curved, and slightly do- 

 ])res.sed from a true circle, in tranverse section, on the ventral 

 side. The outer shell is jn-eserved forward of the fifth septa, 

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

 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- 

 v(>xity 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 

 tlie ventral side the spaces between the furrows are flattene<l 

 and wider than tlie furrows. On the dorsal side the fnn-ows 

 and ridges are sut)e(pial. The body chamber is not completely 

 preserved, and the aperture, therefore, is unknown. 



