Keywords: Conchological Manual Figs 08-09.png Fig 8 Terebratula the tendon passes through a perforation in the upper valve; in Mytilus fig 9 the byssus passes out between the valves gutenberg A Conchological Manual 43417 1842 George Brettingham Sowerby II 1812 “1884 PD-old-100 A conchological manual 1842 Terebratula Unidentified Mytilus Mollusca anatomy |