34 CARBONIFEROUS AMMONOIDS OF AMERICA. 



It is possible that Nomisvioceras may be the connecting link between 

 this family and Prolecanites, although it may be a degenerate form of the 

 Glyphioceratidje, to whicli opinion E. Holzapfel" seems to incline. 



NoMiSMOCERAS ? MONKOENSE Worthen. 



PI. V, tig. 11. 



1890. Goniatltes iiumroensis, A. H. Worthen, Geol. Surv. Illinois, Vol. VIII. p. 1.50. 

 PI. XXVI, %. 5. 



Shell discoidal, evolute, compressed, sides slightly rounded, abdomen 

 narrow and sharply rounded. Height of whorl a little greater than width; 

 umbilicus comparatively wide, being about once and a half as wide as the 

 height of the whorl. Umbilical shoulders rather angular and abrupt. 

 Surface of shell smooth, septa consisting of a pair of short rounded lobes 

 on each side, with obtuse saddles. 



The generic reference is very doubtful; the species certainh^ does not 

 agree with the type of the genus, but probably is as nearly related to it as 

 are several other species that are generally classed under Nomismoceras. 



Occurrence. — Lower Carboniferous, St. Louis stage, Monroe, Illinois. 

 Deposited in the Illinois State Museum. 



Si-Tperfaraily PROLEC^NITID^E. 



Family BELOCERATID.E. 

 Grenus Prodromites Smith and Weller. 



The type of this genus is P. (Goniatites) gorhyi Miller.'' The type 

 species was originally described as ^^ Goniatites,^^ but a most liberal 

 interpretation of that group could not include this form, \vhich was 

 rt.'^signed to that division simply because of its occurrence in Carboniferous 

 rocks. 



The g-fc-'uis I'rodroniites is characterized by its laterally' comjiressed, dis- 

 coidal, involute deeply embracing whorls, narrow umbilicus, liigli, hollow 

 abdominal keel, and complex ceratitic septa. Where the keel is broken off. 



"Die Cephalopoden des Loiiianik im siidlichen Timan, p. 21: Mem. Com. g^ol. Eussie, XII, No. 3. 

 'J Advance sheets Seventeenth Ann. Rept. Geol. Surv. Indiana, p. 90, PI. XV, fig. 1; and Seventeenth 

 Ann. Rept. (ieol. Surv. Indiana, p. 700, PI. XV, fig. 1. 



