Fig. 1 in Conellae, enigmatic structures on cephalopod shells -shapes, distribution, and formation

Fig. 1. Calcite conellae on internal moulds of siphuncle of Middle Ordovician endocerids from Leningrad region of Russia. A. GIN MPC 4/1, conellae in remnants of nautiloid siphuncle endocones; in top (A1) and lateral (A2) views, and close up, lateral view (A3). B. GIN MPC 4/2, single conella on the surface of pointed end of the endocerid siphuncle (spiculum). C. GIN MPC 4/3, single conella on the surface of spiculum, both with longitudinal and horizontal lines; in lateral (C1) and anterior (adapertural) (C2) views. D. GIN MPC 4/4, group of conellae on the spiculum internal mould.