96 CARBONIFEROUS AMMONOIDS OF AMERICA. 



diameter. Surface smooth, but ribs and constrictions might possibly not be 

 preserved by the iron ore by which the shell is replaced. Septa consisting 

 of hastate lobes and tongue-shaped saddles; siphonal saddle long, mucro- 

 nate, ventral saddles long and tongue-shaped, lateral saddle broadly rounded; 

 ventral lobes narrow and hastate, lateral lobes broader and pointed, second 

 lateral or auxiliary lobe on the umbilical border. The antisiphonal lobe 

 is long, narrow, and pointed, flanked by a pair of shorter hastate lobes and 

 narrow tongue-shaped saddles. The internal lateral saddles are very broad 

 and shallow. 



This species seems to be nearest akin to Gastrioceras carhonarimn, with 

 which its form and septa agree, but the smoothness of the shell of G. noU- 

 nense would serve to distinguish them, if it should be proved that the speci- 

 mens are always devoid of ornamentation. 



Occurrence. — Middle Coal Measures, Nolin, Edmonson County, Ky., 

 and Des Moines formation, Middle Coal Measures, of Des Moines, Iowa. 



Gastrioceras occidentale Miller and Faber. 

 PI. VIII, figs. 6 and 7. 



1892. Go7iiatl.tes oceidenfnlh^ Miller and Faber, Jour. Cincinnati Soc. Nat. Hist., 

 Vol. XIV, p. 166, PI. VI. tigs. 6 and 7. 



Shell subglobose, abdomen broadly rounded, sides sloping with a gentle 

 curve to the abrupt umbilical shoulders. Whorls highly arched, deeply 

 embracing, indented to about one-half of their height by the inner whorls. 

 Umbilicus deep and wide, being about one-third of the total diameter. 

 Umbilical shoulder crenulated or subnodose. Surface marked by four 

 broad, shallow constrictions which run nearly straight across the abdomen. 

 Between these furrows are tine transverse lines of growth, parallel to the 

 constrictions. The septa, as shown by Miller and Faber, do not resemble 

 those of any known goniatite genus, but are remarkably like the impres- 

 sions of the internal muscle-scars, as seen on many ammonoids. This is 

 probably what was seen by Miller and Faber and reproduced in the 

 drawing. The septa when seen will jirobably be like those of other species 

 of Gastrioceras. 



Occurrence. — Middle Coal Measures, Elkhorn Creek, Kentucky. 



