... loss of the ribbing on the body-chamber. This decline of ornamentation, however, may also occur in the var. rustica VI I Invertebrate Faunas of the Bathonian-Callovian Deposits of Jameson Land. ... 32 VI I Invertebrate Faunas of the Bathonian-Callovian Deposits of Jameson Land. 2 1 part of the body-chamber, its umbilicus is still narrow. This specimen, at the beginning of the outer ... VII Invertebrate Faunas of the Bathonian-Callovian Deposits of Jameson Land. 29 spicuous narrowing of the outer whorl. The comparison to these two species, however, is misleading, for the...