|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Lingulata - Lingulida - Obolidae
If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
|A. Williams 1962||Pale-brown coloured, elongately oval and gently biconvex Glyptoglossa with the pedicle valve up to twice as long as wide, external surfaces covered by concentric lamellae, initially very closely spaced and regular but anastomosing and becoming frilled and scalloped in later stages of growth and numbering about 9 per miUimetre 10 mm. anterior to the umbo; ventral muscle-field large and elevated, occupying the posterior two-fifths of the shell and extending antero-medianly as a short ridge; dorsal interior including a raised pad of shell substance, with a rounded anterior margin at over one-half the length of the valve and indented by 3 pairs of elongate muscle impressions disposed symmetrically about a strong median septum which comes to a point at its intersection with the front boundary of the muscle pad; beyond the point of intersection a trace of a median ridge extends for a short distance anteriorly, lying between a pair of subparallel raised areas possibly representing pallial sinus impressions.|