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Lagynocystis pyramidalis was first described and figured by Barrande 1887 under the name Anomalocystites pyramidalis. Taxonomy from Parsley, 2000. Lagynocystis pyramidalis (Barrande) from the marine Lower Ordovician of Bohemia, has features which suggest that it is ancestral, or nearly so, to living cephalochordates such as amphioxus (Branchiostoma). Diagnosis from Parsley 2000, p. 258: "Ankyroid with asymmetrical theca. M‘l—M'5 well developed: MI—M3 shortened and reduced in size: M4 and M5 absent; large CS plate. M‘5 protuberant, hollow. Sutures with M’4 and in some specimens narrowly sutured with M'3 but not flexibly articulated. Superior face with distally overlapping platelets that wrap around onto inferior face near posterior ends. Proximal aulacophore with multiplated meres; styloid with four or five denticulate cups; distal aulacophore atypically long with elongate ossicles and tall rectangular cover plates." Line drawing from Parsley 2000, p. 255: References: Barrande, J. (1887). Classe des Echinodermes. Ordre des cystidées, p. 1–233. In Systême silurien du centre de la Bohême, 7. Rivnác (Prague) and Gerhard (Leipzig). Jefferies R. P. S. (1973). The Ordovician fossil Lagynocystis pyramidalis (Barrande) and the ancestry of amphioxus Phil. Trans. R. Soc. Lond. B265, pp. 409–469. Parsley, R. L. (2000). Morphological and Paleoecolgical Analysis of the Ordovician Ankyroid Lagynocystis (Stylophora: Echinodermata). Journal of Paleontology, 74(2), 254–262.

Taxonomy from Fossilworks.org. Reconstruction from Jefferies 1984, p.293: References: Richard P. S. Jefferies (1984) Locomotion, shape, ornament, and external ontogeny in some mitrate calcichordates, Journal of Vertebrate Paleontology, 4:3, 292-319, DOI: 10.1080/02724634.1984.10012011