92 CARBONIFEROUS AMMONOIDS OF AMERICA. 



preceding whorls. Breadth of whorl about two-thirds of the total diameter 

 of the shell and nearly twice as great as the height of the whorl. Umbilicus 

 wide, its width being more than a third of the total diameter of the shell. 

 Surface of the shell smooth, not mai-ked by ribs. 



According to Miller and Gurley , this species differs from G. illinoisense in 

 its larger umbilicus, more depressed whorls, less gibbous shape of the 

 whorls, greater abruptness of the umbilical shoulders, and greater sim- 

 plicity of the septa, which ar6 decidedly mucronate in G. illinoisense and 

 merely tongue-shaped in G. hansasense. Also in G. kansasense the auxiliary 

 lobe is on the umbilical border, while on G. UUnoisense it is on the umbilical 

 slope, just below the shoulder. Both species belong to- the group of G. 

 glohnlosnm, characterized by globose whorls and absence of umbilical nodes 

 or ribs, thus differing from the species that have been considered typical of 

 Gastrioceras. This seems to be a rather specialized group that has lost the 

 nodes entirely, and retains the constrictions only in the young. 



Occurrence. — Upper Coal Measures, Missourian stage, Kansas City, Mo. 

 The type is in the paleontologic collection. Walker Museum, University of 

 Chicago. 



Gastrioceras kingi Hall and Whitfield. 



PI. IV, figs. 4-8. 



1877. Goniatites kingi. Hall and Whitfield, U. S. Geol. Expl. Fortieth Parallel, Vol. 



IV, Pt. II, p. 299. PI. VI, ligs. 9-1-i. 

 1884. GuHtrioci/ranl-hujl, A. Hyatt, Proc. Boston Soc. Nat. Hist., Vol. XXII, p. 327. 



Shell subglobose, the breadth of the whorls being about two thirds of 

 the total diameter of the shell and about twice as great as the height of the 

 whorl. Whorls with flattened broad venter, depressed helmet-shaped out- 

 line, abrupt a!igular umbilical shoulders, the umbilical border havnig an 

 inchnation of 45° with the axis of the shell. Umbilicus wide, being about 

 one-half of the diameter of the shell. Whorls deeply embracing, each one 

 covering the inner whorl to near the umbilical shoulder, and being indented 

 by this to one-half its height. 



Surface ornamented by obscure nodes on the umbilical shoulders, 

 sometimes forming faint undulations across the abdomen. The whole sur- 

 face is covered by fine lines of growth, the crowding together of which 

 causes the undulations. Surface of the cast marked by constrictions, about 

 two to a revolution. 



