Geisonoceras sp. from the Silurian of Poland. 1. Living chamber in ventral view, Late Silurian, borehole Białopole IG (depth of 1670.7 m). 2. Phragrnocone in lateral view (a) and its medial section (b), upper Siedlce beds, Ludlow, borehole Gołdap. 3. Longitudinal section through the siphuncle; erratic boulder, probably early Ludlow, Orłowo.

Geisonoceras sp.; erratic boulders of Baltic origin P. originalis Zone, Volkhovian;

a Reconstruction of the adult livingchamber;

b reconstruction of a phragmocone fragment with calcareous deposits, ZPAL Nj405 ,boulder E-116, Rozewie, Poland;

c section through the siphuncle of the same specimen;