Original Description of Calyptraphorus septentrionalis by Stanton, 1920, p. 39:
- "Shell of medium size, consisting of about 10 nearly flat whorls which in immature shells are covered by numerous fine, threadlike spiral lines and less conspicuous curved costae, which become obsolete on the later whorls. In the adult a heavy flat callus covers the entire front side of the spire, completely concealing the whorls, and a thinner deposit glazes the dorsal aspect, obscuring but not entirely concealing the sutures and the surface sculpture. The fragmentary type, consisting of the larger part of the spire, is 33 millimeters in height and 16 millimeters in greatest breadth and has an apical angle of about 25°. A smaller specimen which is believed to represent an immature stage of this species before the callus was developed is 12 millimeters in height and 8 millimeters in greatest breadth. These two specimens from the same locality are the only known examples of the species."
Stratum typicum: Cannonball Marine Member, Lance Formation, late Maastrichtian, Cretaceous
Locus typicus: Cannonball River, North & South Dakota, USA