Hyolith terminology.

<p>A, Reconstruction of the hyolithid conch <i>Joachimilites novaki </i><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088583#pone.0088583-Marek5" target="_blank">[23]</a> with proturding helens and <i>in situ</i> operculum. External (left) and internal (right) surfaces of operculum are detailed. l: ligula; h: helens; CaS: cardinal shield; r: rooflet; CoS: conical shield; cp: cardinal process; cl: clavicle; modified after <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088583#pone.0088583-Malinky1" target="_blank">[8]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088583#pone.0088583-Malinky4" target="_blank">[56]</a>. B, Reconstruction of the orthothecid conch <i>Nephrotheca housina </i><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088583#pone.0088583-Marek5" target="_blank">[23]</a> with <i>in situ</i> operculum and detail of external (left) and internal (right) surfaces of operculum. p: process; lc: clavicle-like structure; modified after <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088583#pone.0088583-Marek5" target="_blank">[23]</a>.