- GeoRef, Copyright 2004, American Geological Institute. Reference includes data from Bibliography and Index of Geology Exclusive of North America, Geological Society of America, Boulder, CO, United States
In anticipation of a condensed standard description of the Nummulites species in general, this article proposes a more extensive use of the graphic presentation of essential diagnostic features of the equatorial section of the microspheric generation. The comprehensive graph in question consists of four curves: 1) the well-known winding curve (connecting the radii of the successive whorls), which roughly reflects the opening step of the spire; 2) the file of the numbers of chambers per whorl on the same scale of whorls; 3) the height of the chamber lumen; and 4) this same height plus the thickness of the spiral cord or lamina. The latter two curves, representing an analysis of the spiral step, confine an irregular ribbon which delineates the thickness of the spinal cord or lamina over the whole spire. The combination of four curves over the same abscissa unveils certain breaks and trends in the course of the spire (or the course of the specimen's life) which hitherto remained unrecorded.