Figure 2.Ceratreta hebes dorsal valve exterior (a, ×18), interior (b, ×18), and oblique interior, illustrating the median septum (c, ×21); ventral valve exterior, apical view (d, ×15), illustrating the slit-like apical foramen, oblique lateral view (e, ×18) and posterior view (f, ×16); ventral valve interior (g, ×14). Each image shows a valve with a diameter that measures 2 mm (0.08 in.). [After R. L. Kaesler, ed., Treatise on Invertebrate Paleontology, pt. H: Brachiopoda, rev. vol. 2, Geological Society of America/University of Kansas Press, Boulder, CO/Lawrence, KS, 2000; adapted from L. E. Holmer and L. E. Popov, The acrotretacean brachiopod Ceratreta tanneri (Metzger) from the Upper Cambrian of Baltoscandia, Geol. Foren. Stockh. Forh., 112:249–263, 1990]
