Dr. Nagy I. Zoltán szerk.: Fragmenta Mineralogica Et Palaentologica 7. 1976. (Budapest, 1976)
Genera Characters Nummulites Operculina Assilina Rhanikothalia Operculinoides Shape Lenticular, flat, globose Complanate lenticular Lenticular, flat low lenticular to nearly flat low lenticular Form Involute Evolute to partially involute Evolute Involute to partially evolute Involute mostly some tending to be evolute. Chamber tops as seen in equatorial section Acute angle posteriorly As in Nummulites As in Nummulites Bluntly round generally type species as in Nummulites Whorl wall Single, not differentiated canaliculate As in Nummulites spiral canal tend to be more numbers like Nummulites Double, inner simple, outer coarsely canaliculate degenerate" type species as in Nummulites Whorls many variable generally few many variable generally few few to many Height of coils typically slowly increasing or variable Rapidly increasing typically slowly increasing rapidly variable rapidly increasing Table 1. The distribution of the various structural featuers among the most Important genera of subfamily Nummulitinae .
